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94-429: The principal importance of GaInAs is its application as a high-speed, high sensitivity photodetector of choice for optical fiber telecommunications. Indium gallium arsenide (InGaAs) and gallium-indium arsenide (GaInAs) are used interchangeably. According to IUPAC standards the preferred nomenclature for the alloy is Ga x In 1-x As where the group-III elements appear in order of increasing atomic number, as in

188-426: A FinFET device configuration. The results of this test sparked more research, by the same research team, into transistors made of InGaAs which showed that in terms of on current at lower supply voltage, InGaAs performed very well compared to existing silicon devices. In Feb 2015 Intel indicated it may use InGaAs for its 7 nanometer CMOS process in 2017. The synthesis of GaInAs, like that of GaAs, most often involves

282-537: A coding system that represented long sequences of amino acids. This would allow for these sequences to be compared to try to find homologies . These codes can consist of either a one-letter code or a three-letter code. These codes make it easier and shorter to write down the amino acid sequences that make up proteins . The nucleotide bases are made up of purines ( adenine and guanine ) and pyrimidines ( cytosine and thymine or uracil ). These nucleotide bases make up DNA and RNA . These nucleotide base codes make

376-434: A few percent. Therefore, the properties of epitaxial films of GaInAs alloys grown on GaAs are very similar to GaAs and those grown on InAs are very similar to InAs, because lattice mismatch strain does not generally permit significant deviation of the composition from the pure binary substrate. Ga 0.47 In 0.53 As is the alloy whose lattice parameter matches that of InP at 295 K. GaInAs lattice-matched to InP

470-408: A gap between bands. The behavior of the one-dimensional situations does not occur for two-dimensional cases because there are extra freedoms of motion. Furthermore, a bandgap can be produced with strong periodic potential for two-dimensional and three-dimensional cases. Based on their band structure, materials are characterised with a direct band gap or indirect band gap. In the free-electron model, k

564-456: A lattice parameter that increases linearly with the concentration of InAs in the alloy. The liquid-solid phase diagram shows that during solidification from a solution containing GaAs and InAs, GaAs is taken up at a much higher rate than InAs, depleting the solution of GaAs. During growth from solution, the composition of first material to solidify is rich in GaAs while the last material to solidify

658-402: A material with a large band gap is an insulator . In conductors , the valence and conduction bands may overlap, so there is no longer a bandgap with forbidden regions of electronic states. The conductivity of intrinsic semiconductors is strongly dependent on the band gap. The only available charge carriers for conduction are the electrons that have enough thermal energy to be excited across

752-1014: A member state of the Chemical Weapons Convention (CWC), are of concern to chemical scientists and engineers around the globe and we stand ready to support your mission of implementing the CWC." According to the CWC, "the use, stockpiling, distribution, development or storage of any chemical weapons is forbidden by any of the 192 state party signatories." IUPAC is governed by several committees that all have different responsibilities. The committees are as follows: Bureau, CHEMRAWN (Chem Research Applied to World Needs) Committee, Committee on Chemistry Education, Committee on Chemistry and Industry, Committee on Printed and Electronic Publications, Evaluation Committee, Executive Committee, Finance Committee, Interdivisional Committee on Terminology, Nomenclature and Symbols, Project Committee, and Pure and Applied Chemistry Editorial Advisory Board. Each committee

846-410: A number of bands of energy, and forbidden from other regions because there are no allowable electronic states for them to occupy. The term "band gap" refers to the energy difference between the top of the valence band and the bottom of the conduction band. Electrons are able to jump from one band to another. However, in order for a valence band electron to be promoted to the conduction band, it requires

940-401: A perfect lattice match to Ge. The perfect lattice match to Ge reduces defect density, improving cell efficiency. HEMT devices using InGaAs channels are one of the fastest types of transistor In 2012 MIT researchers announced the smallest transistor ever built from a material other than silicon. The Metal oxide semiconductor field-effect transistor ( MOSFET ) is 22 nanometers long. This

1034-585: A photodiode design that exploits the uniquely short diffusion time of high mobility of electrons in GaInAs, leading to an ultrafast response time. This structure was further developed and subsequently named the UTC, or uni-travelling carrier photodiode. In 1989, Wey and co-workers designed and demonstrated a p-i-n GaInAs/InP photodiodes with a response time shorter than 5 picoseconds for a detector surface measuring 5 μm x 5 μm. Other important innovations include

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1128-481: A photon and phonon must both be involved in a transition from the valence band top to the conduction band bottom, involving a momentum change . Therefore, direct bandgap materials tend to have stronger light emission and absorption properties and tend to be better suited for photovoltaics (PVs), light-emitting diodes (LEDs), and laser diodes ; however, indirect bandgap materials are frequently used in PVs and LEDs when

1222-413: A regular semiconductor crystal, the band gap is fixed owing to continuous energy states. In a quantum dot crystal, the band gap is size dependent and can be altered to produce a range of energies between the valence band and conduction band. It is also known as quantum confinement effect . Band gaps can be either direct or indirect , depending on the electronic band structure of the material. It

1316-607: A role in determining a material's informal classification. The band-gap energy of semiconductors tends to decrease with increasing temperature. When temperature increases, the amplitude of atomic vibrations increase, leading to larger interatomic spacing. The interaction between the lattice phonons and the free electrons and holes will also affect the band gap to a smaller extent. The relationship between band gap energy and temperature can be described by Varshni 's empirical expression (named after Y. P. Varshni ), Furthermore, lattice vibrations increase with temperature, which increases

1410-404: A single crystal substrate of III-V semiconductor having a lattice parameter close to that of the specific gallium indium arsenide alloy to be synthesized. Three substrates can be used: GaAs, InAs and InP. A good match between the lattice constants of the film and substrate is required to maintain single crystal properties and this limitation permits small variations in composition on the order of

1504-506: A specific minimum amount of energy for the transition. This required energy is an intrinsic characteristic of the solid material. Electrons can gain enough energy to jump to the conduction band by absorbing either a phonon (heat) or a photon (light). A semiconductor is a material with an intermediate-sized, non-zero band gap that behaves as an insulator at T=0K, but allows thermal excitation of electrons into its conduction band at temperatures that are below its melting point. In contrast,

1598-421: Is cyclohexanol : Basic IUPAC inorganic nomenclature has two main parts: the cation and the anion . The cation is the name for the positively charged ion and the anion is the name for the negatively charged ion. An example of IUPAC nomenclature of inorganic chemistry is potassium chlorate (KClO 3 ): IUPAC also has a system for giving codes to identify amino acids and nucleotide bases. IUPAC needed

1692-478: Is 0.75 eV and lies between that of Ge and Si. By coincidence the bandgap of GaInAs is perfectly placed for photodetector and laser applications for the long-wavelength transmission window, (the C-band and L-band) for fiber-optic communications . The electron effective mass of GaInAs m/m° = 0.041 is the smallest for any semiconductor material with an energy bandgap greater than 0.5 eV. The effective mass

1786-689: Is Germany. Germany's exclusion was a result of prejudice towards Germans by the Allied powers after World War I . Germany was finally admitted into IUPAC in 1929. However, Nazi Germany was removed from IUPAC during World War II . During World War II, IUPAC was affiliated with the Allied powers , but had little involvement during the war effort itself. After the war, East and West Germany were readmitted to IUPAC in 1973. Since World War II, IUPAC has been focused on standardizing nomenclature and methods in science without interruption. In 2016, IUPAC denounced

1880-651: Is a book about soil structures and the molecular processes that occur in soil. Structure and Surface Reactions of Soil Particles is aimed at any researcher researching soil or in the field of anthropology . It goes into depth on topics such as: fractal analysis of particle dimensions; computer modeling of the structure; reactivity of humics; applications of atomic force microscopy; and advanced instrumentation for analysis of soil particles. Metal Speciation and Bioavailability in Aquatic Systems, Series on Analytical and Physical Chemistry of Environmental Systems Vol. 3

1974-468: Is a book about the effect of trace metals on aquatic life. This book is considered a specialty book for researchers interested in observing the effect of trace metals in the water supply. This book includes techniques to assess how bioassays can be used to evaluate how an organism is affected by trace metals. Also, Metal Speciation and Bioavailability in Aquatic Systems, Series on Analytical and Physical Chemistry of Environmental Systems Vol. 3 looks at

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2068-407: Is a book that delves into aerosol science. This book is aimed as a reference for graduate students and atmospheric researchers. Atmospheric Particles goes into depth on the properties of aerosols in the atmosphere and their effect. Topics covered in this book are: acid rain ; heavy metal pollution; global warming ; and photochemical smog. Atmospheric Particles also covers techniques to analyze

2162-463: Is a book that discusses techniques and devices to monitor aquatic systems and how new devices and techniques can be developed. This book emphasizes the future use of micro-analytical monitoring techniques and microtechnology . In Situ Monitoring of Aquatic Systems: Chemical Analysis and Speciation is aimed at researchers and laboratories that analyze aquatic systems such as rivers, lakes, and oceans. Structure and Surface Reactions of Soil Particles

2256-517: Is a book that gives background information on thermal analysis and calorimetry . Thermoanalytical and calorimetric techniques along with thermodynamic and kinetic properties are also discussed. Later volumes of this book discuss the applications and principles of these thermodynamic and kinetic methods. Equations of State for Fluids and Fluid Mixtures Part I is a book that gives up to date equations of state for fluids and fluid mixtures. This book covers all ways to develop equations of state. It gives

2350-460: Is a promising accomplishment, but more work is needed to show that the reduced size results in improved electronic performance relative to that of silicon or GaAs-based transistors. In 2014, Researchers at Penn State University developed a novel device prototype designed to test nanowires made of compound semiconductors such as InGaAs. The goal of this device was to see if a compound material would retain its superior mobility at nanoscale dimensions in

2444-498: Is a semiconductor with properties quite different from GaAs, InAs or InP. It has an energy band gap of 0.75 eV, an electron effective mass of 0.041 and an electron mobility close to 10,000 cm·V·s at room temperature, all of which are more favorable for many electronic and photonic device applications when compared to GaAs, InP or even Si. Measurements of the band gap and electron mobility of single-crystal GaInAs were first published by Takeda and co-workers. Like most materials,

2538-592: Is also known for standardizing the atomic weights of the elements through one of its oldest standing committees, the Commission on Isotopic Abundances and Atomic Weights (CIAAW). The need for an international standard for chemistry was first addressed in 1860 by a committee headed by German scientist Friedrich August Kekulé von Stradonitz . This committee was the first international conference to create an international naming system for organic compounds . The ideas that were formulated at that conference evolved into

2632-726: Is an international federation of National Adhering Organizations working for the advancement of the chemical sciences, especially by developing nomenclature and terminology. It is a member of the International Science Council (ISC). IUPAC is registered in Zürich , Switzerland , and the administrative office, known as the "IUPAC Secretariat", is in Research Triangle Park , North Carolina , United States . IUPAC's executive director heads this administrative office, currently Greta Heydenrych. IUPAC

2726-512: Is deposited as a thin film on a substrate, it is basically inert and is resistant to abrasion, sublimation or dissolution by common solvents such as water, alcohols or acetones . In device form the volume of the GaInAs is usually less than 1000  μm , and can be neglected compared to the volume of the supporting substrate, InP or GaAs. The National Institutes of Health studied these materials and found: The World Health Organization 's International Agency for Research on Cancer 's review of

2820-569: Is determined from the curvature of the energy-momentum relationship: stronger curvature translates into lower effective mass and a larger radius of delocalization. In practical terms, a low effective mass leads directly to high carrier mobility, favoring higher speed of transport and current carrying capacity. A lower carrier effective mass also favors increased tunneling current, a direct result of delocalization. The valence band has two types of charge carriers: light holes: m/m° = 0.051 and heavy holes: m/m° = 0.2. The electrical and optical properties of

2914-832: Is made up of members of different National Adhering Organizations from different countries. The steering committee hierarchy for IUPAC is as follows: Chemical Nomenclature and Structure Representation Division (Division VIII) Current officers of the Executive Committee : Scientists framed a systematic method for naming organic compounds based on their structures. Hence, the naming rules were formulated by IUPAC. IUPAC establishes rules for harmonized spelling of some chemicals to reduce variation among different local English-language variants. For example, they recommend " aluminium " rather than "aluminum", " sulfur " rather than "sulphur", and " caesium " rather than "cesium". IUPAC organic nomenclature has three basic parts:

Indium gallium arsenide - Misplaced Pages Continue

3008-465: Is meant to be a compilation of other IUPAC works. The second edition of this book was published in 1997. This book made large changes to the first edition of the Compendium of Chemical Terminology . These changes included updated material and an expansion of the book to include over seven thousand terms. The second edition was the topic of an IUPAC XML project. This project made an XML version of

3102-483: Is meant to give an overview of a technique based on fractal geometry and the processes of environmental systems. This book gives ideas on how to use fractal geometry to compare and contrast different ecosystems . It also gives an overview of the knowledge needed to solve environmental problems. Finally, Biophysical Chemistry of Fractal Structures and Processes in Environmental Systems shows how to use

3196-416: Is modified to match the absorption profile of the solar cell. Below are band gap values for some selected materials. For a comprehensive list of band gaps in semiconductors, see List of semiconductor materials . In materials with a large exciton binding energy, it is possible for a photon to have just barely enough energy to create an exciton (bound electron–hole pair), but not enough energy to separate

3290-479: Is possible to extend the cut-off wavelength up to about λ=2.6 μm. In that case special measures have to be taken to avoid mechanical strain from differences in lattice constants . GaAs is lattice-mismatched to germanium (Ge) by 0.08%. With the addition of 1.5% InAs to the alloy, In 0.015 Ga 0.985 As becomes latticed-matched to the Ge substrate, reducing stress in subsequent deposition of GaAs. InGaAs has

3384-759: Is relatively well received as being useful for reviewing chemical toxicology. Macromolecular Symposia is a journal that publishes fourteen issues a year. This journal includes contributions to the macromolecular chemistry and physics field. The meetings of IUPAC are included in this journal along with the European Polymer Federation , the American Chemical Society , and the Society of Polymer Science in Japan. The Experimental Thermodynamics books series covers many topics in

3478-528: Is richer in InAs. This feature has been exploited to produce ingots of InGaAs with graded composition along the length of the ingot. However, the strain introduced by the changing lattice constant causes the ingot to be polycrystalline and limits the characterization to a few parameters, such as bandgap and lattice constant with uncertainty due to the continuous compositional grading in these samples. Single crystal epitaxial films of GaInAs can be deposited on

3572-533: Is the Compendium of Analytical Nomenclature (the "Orange Book"; 1st edition 1978). This book was revised in 1987. The second edition has many revisions that come from reports on nomenclature between 1976 and 1984. In 1992, the second edition went through many different revisions, which led to the third edition. Pure and Applied Chemistry is the official monthly journal of IUPAC. This journal debuted in 1960. The goal statement for Pure and Applied Chemistry

3666-486: Is the final orbital, ʃ φ f ûεφ i is the integral, ε is the electric vector, and u is the dipole moment. Two-dimensional structures of solids behave because of the overlap of atomic orbitals. The simplest two-dimensional crystal contains identical atoms arranged on a square lattice. Energy splitting occurs at the Brillouin zone edge for one-dimensional situations because of a weak periodic potential, which produces

3760-497: Is the largest of currently-used semiconductors. The principal application of GaInAs is as an infrared detector . The spectral response of a GaInAs photodiode is shown in Figure 5. GaInAs photodiodes are the preferred choice in the wavelength range of 1.1 μm < λ < 1.7 μm. For example, compared to photodiodes made from Ge, GaInAs photodiodes have faster time response, higher quantum efficiency and lower dark current for

3854-403: Is the momentum of a free electron and assumes unique values within the Brillouin zone that outlines the periodicity of the crystal lattice. If the momentum of the lowest energy state in the conduction band and the highest energy state of the valence band of a material have the same value, then the material has a direct bandgap. If they are not the same, then the material has an indirect band gap and

Indium gallium arsenide - Misplaced Pages Continue

3948-769: Is the recognized world authority in developing standards for naming the chemical elements and compounds . Since its creation, IUPAC has been run by many different committees with different responsibilities. These committees run different projects which include standardizing nomenclature , finding ways to bring chemistry to the world, and publishing works. IUPAC is best known for its works standardizing nomenclature in chemistry, but IUPAC has publications in many science fields including chemistry, biology, and physics. Some important work IUPAC has done in these fields includes standardizing nucleotide base sequence code names; publishing books for environmental scientists, chemists, and physicists; and improving education in science. IUPAC

4042-443: Is to "publish highly topical and credible works at the forefront of all aspects of pure and applied chemistry." The journal itself is available by subscription, but older issues are available in the archive on IUPAC's website. Pure and Applied Chemistry was created as a central way to publish IUPAC endorsed articles. Before its creation, IUPAC did not have a quick, official way to distribute new chemistry information. Its creation

4136-454: Is unusual in two regards: The room temperature electron mobility for reasonably pure samples of Ga 0.47 In 0.53 As approaches 10 × 10 cm ·V·s, which is the largest of any technologically important semiconductor, although significantly less than that for graphene . The mobility is proportional to the carrier conductivity. As mobility increases, so does the current-carrying capacity of transistors. A higher mobility shortens

4230-471: The HOMO/LUMO gap in chemistry. If the valence band is completely full and the conduction band is completely empty, then electrons cannot move within the solid because there are no available states. If the electrons are not free to move within the crystal lattice, then there is no generated current due to no net charge carrier mobility. However, if some electrons transfer from the valence band (mostly full) to

4324-609: The quantum cascade laser (QCL). The energy of photon emission is a fraction of the bandgap energy. For example, GaInAs/ AlInAs QCL operates at room temperature in the wavelength range 3 μm < λ < 8 μm. The wavelength can be changed by modifying the width of the GaInAs quantum well. These lasers are widely used for chemical sensing and pollution control. GaInAs is used in triple-junction photovoltaics and also for thermophotovoltaic power generation. In 0.015 Ga 0.985 As can be used as an intermediate band-gap junction in multi-junction photovoltaic cells with

4418-420: The substituents , carbon chain length, and chemical affix. The substituents are any functional groups attached to the main carbon chain. The main carbon chain is the longest possible continuous chain. The chemical affix denotes what type of molecule it is. For example, the ending ane denotes a single bonded carbon chain, as in "hexane" ( C 6 H 14 ). Another example of IUPAC organic nomenclature

4512-425: The λ = 1500 nm low-loss, low-dispersion window for optical fiber telecommunications In 1994, GaInAs/ AlInAs quantum wells were used by Jérôme Faist and co-workers who invented and demonstrated a new kind of semiconductor laser based on photon emission by an electron making an optical transition between subbands in the quantum well. They showed that the photon emission regions can be cascaded in series, creating

4606-589: The IUPAC Council during the General Assembly. Below is the list of IUPAC Presidents since its inception in 1919. Band gap In solid-state physics and solid-state chemistry , a band gap , also called a bandgap or energy gap , is an energy range in a solid where no electronic states exist. In graphs of the electronic band structure of solids, the band gap refers to the energy difference (often expressed in electronvolts ) between

4700-459: The NIH toxicology study concluded: REACH ( Registration, Evaluation, Authorisation and Restriction of Chemicals ) is a European initiative to classify and regulate materials that are used, or produced (even as waste) in manufacturing. REACH considers three toxic classes: carcinogenic, reproductive, and mutagenic capacities. The REACH classification procedure consists of two basic phases. In phase one

4794-549: The Pacific Ocean are a result of reduced chlorophyll for phytoplankton production. It does this by reviewing information from research in the 1990s. This book goes into depth about: chemical speciation; analytical techniques; transformation of iron; how iron limits the development of high nutrient low chlorophyll areas in the Pacific Ocean . In Situ Monitoring of Aquatic Systems: Chemical Analysis and Speciation

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4888-633: The Terrestrial Ecosystem gives techniques to analyze minerals, microorganisms, and organic components together. This book also has a large section positing why environmental scientists working in the specific fields of minerals, microorganisms, and organic components of soil should work together and how they should do so. The Biogeochemistry of Iron in Seawater is a book that describes how low concentrations of iron in Antarctica and

4982-500: The Terrestrial Ecosystem is about how minerals, microorganisms, and organic components work together to affect terrestrial systems . This book identifies that there are many different techniques and theories about minerals, microorganisms, and organic components individually, but they are not often associated with each other. It further goes on to discuss how these components of soil work together to affect terrestrial life. Interactions Between Soil Particles and Microorganisms: Impact on

5076-487: The Thermodynamic Properties of Multiple Phases is a book that includes multiple techniques that are used to study multiple phases of pure component systems. Also included in this book are the measurement techniques to obtain activity coefficients , interfacial tension , and critical parameters . This book was written for researchers and graduate students as a reference source. Atmospheric Particles

5170-423: The Thermodynamic Properties of Single Phases is a book that gives an overview of techniques for measuring the thermodynamic quantities of single phases. It also goes into experimental techniques to test many different thermodynamic states precisely and accurately. Measurement of the Thermodynamic Properties of Single Phases was written for people interested in measuring thermodynamic properties. Measurement of

5264-704: The atmosphere and ways to take atmospheric samples. Environmental Colloids and Particles: Behaviour, Separation and Characterisation is a book that discusses environmental colloids and current information available on them. This book focuses on environmental colloids and particles in aquatic systems and soils. It also goes over techniques such as techniques for sampling environmental colloids, size fractionation, and how to characterize colloids and particles. Environmental Colloids and Particles: Behaviour, Separation and Characterisation also delves into how these colloids and particles interact. Biophysical Chemistry of Fractal Structures and Processes in Environmental Systems

5358-444: The band gap and the electron holes that are left off when such an excitation occurs. Band-gap engineering is the process of controlling or altering the band gap of a material by controlling the composition of certain semiconductor alloys , such as GaAlAs , InGaAs , and InAlAs . It is also possible to construct layered materials with alternating compositions by techniques like molecular-beam epitaxy . These methods are exploited in

5452-554: The book that includes over seven thousand terms. The XML version of the book includes an open editing policy, which allows users to add excerpts of the written version. IUPAC and UNESCO were the lead organizations coordinating events for the International Year of Chemistry , which took place in 2011. The International Year of Chemistry was originally proposed by IUPAC at the general assembly in Turin , Italy. This motion

5546-442: The conduction band (mostly empty), then current can flow (see carrier generation and recombination ). Therefore, the band gap is a major factor determining the electrical conductivity of a solid. Substances having large band gaps (also called "wide" band gaps) are generally insulators , those with small band gaps (also called "narrow" band gaps) are semiconductor , and conductors either have very small band gaps or none, because

5640-475: The design of heterojunction bipolar transistors (HBTs), laser diodes and solar cells . The distinction between semiconductors and insulators is a matter of convention. One approach is to think of semiconductors as a type of insulator with a narrow band gap. Insulators with a larger band gap, usually greater than 4 eV, are not considered semiconductors and generally do not exhibit semiconductive behaviour under practical conditions. Electron mobility also plays

5734-402: The distinction may be significant. In photonics , band gaps or stop bands are ranges of photon frequencies where, if tunneling effects are neglected, no photons can be transmitted through a material. A material exhibiting this behaviour is known as a photonic crystal . The concept of hyperuniformity has broadened the range of photonic band gap materials, beyond photonic crystals. By applying

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5828-470: The effect of an equipment setup on an experiment. Fundamental Toxicology is a textbook that proposes a curriculum for toxicology courses. Fundamental Toxicology is based on the book Fundamental Toxicology for Chemists . Fundamental Toxicology is enhanced through many revisions and updates. New information added in the revisions includes: risk assessment and management; reproductive toxicology; behavioral toxicology; and ecotoxicology . This book

5922-401: The effect of electron scattering. Additionally, the number of charge carriers within a semiconductor will increase, as more carriers have the energy required to cross the band-gap threshold and so conductivity of semiconductors also increases with increasing temperature. The external pressure also influences the electronic structure of semiconductors and, therefore, their optical band gaps. In

6016-596: The effects of ingesting GaAs or InP dust in a liquid slurry. The REACH procedure, acting under the precautionary principle , interprets "inadequate evidence for carcenogenicity" as "possible carcinogen". As a result, the European Chemicals Agency classified InP in 2010 as a carcinogen and reproductive toxin: and ECHA classified GaAs in 2010 as a carcinogen and reproductive toxin: IUPAC The International Union of Pure and Applied Chemistry ( IUPAC / ˈ aɪ juː p æ k , ˈ juː -/ )

6110-403: The electron and hole (which are electrically attracted to each other). In this situation, there is a distinction between "optical band gap" and "electronic band gap" (or "transport gap"). The optical bandgap is the threshold for photons to be absorbed, while the transport gap is the threshold for creating an electron–hole pair that is not bound together. The optical bandgap is at lower energy than

6204-400: The electronic transition must undergo momentum transfer to satisfy conservation. Such indirect "forbidden" transitions still occur, however at very low probabilities and weaker energy. For materials with a direct band gap, valence electrons can be directly excited into the conduction band by a photon whose energy is larger than the bandgap. In contrast, for materials with an indirect band gap,

6298-522: The fields of thermodynamics. Measurement of the Transport Properties of Fluids is a book that is published by Blackwell Science . The topics that are included in this book are low and high-temperature measurements, secondary coefficients, diffusion coefficients , light scattering , transient methods for thermal conductivity , methods for thermal conductivity, falling-body viscometers, and vibrating viscometers . Solution Calorimetry

6392-494: The first to describe single-crystal epitaxial growth of In 0.53 Ga 0.47 As on (111)-oriented and on (100)-oriented InP substrates. Single crystal material in thin-film form can be grown by epitaxy from the liquid-phase (LPE), vapour-phase (VPE), by molecular beam epitaxy (MBE), and by metalorganic chemical vapour deposition (MO-CVD). Today, most commercial devices are produced by MO-CVD or by MBE. The optical and mechanical properties of InGaAs can be varied by changing

6486-530: The fractal approach to understand the reactivity of flocs , sediments, soils, microorganisms, and humic substances. Interactions Between Soil Particles and Microorganisms: Impact on the Terrestrial Ecosystem is meant to be read by chemists and biologists that study environmental systems. Also, this book should be used as a reference for earth scientists, environmental geologists, environmental engineers, and professionals in microbiology and ecology. Interactions Between Soil Particles and Microorganisms: Impact on

6580-467: The genome of an organism much smaller and easier to read. The codes for amino acids (24 amino acids and three special codes) are: Principles and Practices of Method Validation is a book entailing methods of validating and analyzing many analytes taken from a single aliquot . Also, this book goes over techniques for analyzing many samples at once. Some methods discussed include chromatographic methods, estimation of effects, matrix-induced effects, and

6674-554: The growth temperature, it is necessary to increase the GaAs mole fraction to 0.48. The bandgap energy of GaInAs can be determined from the peak in the photoluminescence spectrum, provided that the total impurity and defect concentration is less than 5 × 10  cm. The bandgap energy depends on temperature and increases as the temperature decreases, as can be seen in Fig. 3 for both n-type and p-type samples. The bandgap energy at room temperature for standard InGaAs/InP (53% InAs, 47% GaAs),

6768-774: The hazards intrinsic to the material are determined, without any consideration of how the material might be used or encountered in the work place or by a consumer. In phase two the risk of harmful exposure is considered along with procedures that can mitigate exposure. Both GaAs and InP are in phase 1 evaluation. The principal exposure risk occurs during substrate preparation where grinding and polishing generate micron-size particles of GaAs and InP. Similar concerns apply to wafer dicing to make individual devices. This particle dust can be absorbed by breathing or ingestion. The increased ratio of surface area to volume for such particles increases their chemical reactivity. Toxicology studies are based on rat and mice experiments. No comparable studies test

6862-468: The integrated photodiode – FET receiver and the engineering of GaInAs focal-plane arrays. Semiconductor lasers are an important application for GaInAs, following photodetectors. GaInAs can be used as a laser medium. Devices have been constructed that operate at wavelengths of 905 nm, 980 nm, 1060 nm, and 1300 nm. InGaAs quantum dots on GaAs have also been studied as lasers. GaInAs/ InAlAs quantum-well lasers can be tuned to operate at

6956-437: The lattice parameter of GaInAs is a function of temperature. The measured coefficient of thermal expansion is 5.66 × 10  K. This is significantly larger than the coefficient for InP which is 4.56 × 10  K. A film that is exactly lattice-matched to InP at room temperature is typically grown at 650 °C with a lattice mismatch of + 6.5 × 10 . Such a film has a mole fraction of GaAs = 0.47. To obtain lattice matching at

7050-742: The limitations of the use of bioassays to observe the effects of trace metals on organisms. Physicochemical Kinetics and Transport at Biointerfaces is a book created to aid environmental scientists in fieldwork. The book gives an overview of chemical mechanisms, transport, kinetics, and interactions that occur in environmental systems . Physicochemical Kinetics and Transport at Biointerfaces continues from where Metal Speciation and Bioavailability in Aquatic Systems leaves off. IUPAC color code their books in order to make each publication distinguishable. One extensive book on almost all nomenclature written (IUPAC nomenclature of organic chemistry and IUPAC nomenclature of inorganic chemistry) by IUPAC committee

7144-461: The materials have other favorable properties. LEDs and laser diodes usually emit photons with energy close to and slightly larger than the band gap of the semiconductor material from which they are made. Therefore, as the band gap energy increases, the LED or laser color changes from infrared to red, through the rainbow to violet, then to UV. The optical band gap (see below) determines what portion of

7238-441: The official IUPAC nomenclature of organic chemistry . IUPAC stands as a legacy of this meeting, making it one of the most important historical international collaborations of chemistry societies . Since this time, IUPAC has been the official organization held with the responsibility of updating and maintaining official organic nomenclature . IUPAC as such was established in 1919. One notable country excluded from this early IUPAC

7332-453: The ratio of InAs and GaAs, In 1-x Ga x As . Most InGaAs devices are grown on indium phosphide (InP) substrates. In order to match the lattice constant of InP and avoid mechanical strain, In 0.53 Ga 0.47 As is used. This composition has an optical absorption edge at 0.75 eV, corresponding to a cut-off wavelength of λ=1.68  μm at 295 K. By increasing the mole fraction of InAs further compared to GaAs, it

7426-416: The related alloy system Al x Ga 1-x As. By far, the most important alloy composition from technological and commercial standpoints is Ga 0.47 In 0.53 As, which can be deposited in single crystal form on indium phosphide (InP). GaInAs is not a naturally-occurring material. Single crystal material is required for electronic and photonic device applications. Pearsall and co-workers were

7520-514: The response time of photodetectors . A larger mobility reduces series resistance, and this improves device efficiency and reduces noise and power consumption. The minority carrier diffusion constant is directly proportional to carrier mobility. The room temperature diffusion constant for electrons at 250 cm ·s is significantly larger than that of Si, GaAs, Ge or InP, and determines the ultra-fast response of Ga 0.47 In 0.53 As photodetectors. The ratio of electron to hole mobility

7614-548: The same sensor area. GaInAs photodiodes were invented in 1977 by Pearsall. Avalanche photodiodes offer the advantage of additional gain at the expense of response time. These devices are especially useful for detection of single photons in applications such as quantum key distribution where response time is not critical. Avalanche photodetectors require a special structure to reduce reverse leakage current due to tunnelling. The first practical avalanche photodiodes were designed and demonstrated in 1979. In 1980, Pearsall developed

7708-403: The solar spectrum a photovoltaic cell absorbs. Strictly, a semiconductor will not absorb photons of energy less than the band gap; whereas most of the photons with energies exceeding the band gap will generate heat. Neither of them contribute to the efficiency of a solar cell. One way to circumvent this problem is based on the so-called photon management concept, in which case the solar spectrum

7802-479: The strengths and weaknesses of each equation. Some equations discussed include: virial equation of state cubic equations; generalized Van der Waals equations ; integral equations; perturbation theory; and stating and mixing rules. Other things that Equations of State for Fluids and Fluid Mixtures Part I goes over are: associating fluids, polymer systems, polydisperse fluids, self-assembled systems, ionic fluids, and fluids near their critical points. Measurement of

7896-418: The top of the valence band and the bottom of the conduction band in insulators and semiconductors . It is the energy required to promote an electron from the valence band to the conduction band. The resulting conduction-band electron (and the electron hole in the valence band) are free to move within the crystal lattice and serve as charge carriers to conduct electric current . It is closely related to

7990-419: The transport gap. In almost all inorganic semiconductors, such as silicon, gallium arsenide, etc., there is very little interaction between electrons and holes (very small exciton binding energy), and therefore the optical and electronic bandgap are essentially identical, and the distinction between them is ignored. However, in some systems, including organic semiconductors and single-walled carbon nanotubes ,

8084-406: The use of arsine ( AsH 3 ), an extremely toxic gas. Synthesis of InP likewise most often involves phosphine ( PH 3 ). Inhalation of these gases neutralizes oxygen absorption by the bloodstream and can be fatal within a few minutes if toxic dose levels are exceeded. Safe handling involves using a sensitive toxic gas detection system and self-contained breathing apparatus. Once GaInAs

8178-607: The use of chlorine as a chemical weapon . The organization pointed out their concerns in a letter to Ahmet Üzümcü, the director of the Organisation for the Prohibition of Chemical Weapons (OPCW), in regards to the practice of utilizing chlorine for weapon usage in Syria among other locations. The letter stated, "Our organizations deplore the use of chlorine in this manner. The indiscriminate attacks, possibly carried out by

8272-502: The valence and conduction bands overlap to form a continuous band. Every solid has its own characteristic energy-band structure . This variation in band structure is responsible for the wide range of electrical characteristics observed in various materials. Depending on the dimension, the band structure and spectroscopy can vary. The different types of dimensions are as listed: one dimension, two dimensions, and three dimensions. In semiconductors and insulators, electrons are confined to

8366-657: The valence band are dominated by the heavy holes, because the density of these states is much greater than that for light holes. This is also reflected in the mobility of holes at 295 K, which is a factor of 40 lower than that for electrons. Electron mobility and hole mobility are key parameters for design and performance of electronic devices. Takeda and co-workers were the first to measure electron mobility in epitaxial films of InGaAs on InP substrates. Measured carrier mobilities for electrons and holes are shown in Figure 4. The mobility of carriers in Ga 0.47 In 0.53 As

8460-529: Was adopted by UNESCO at a meeting in 2008. The main objectives of the International Year of Chemistry were to increase public appreciation of chemistry and gain more interest in the world of chemistry . This event is also being held to encourage young people to get involved and contribute to chemistry. A further reason for this event being held is to honour how chemistry has made improvements to everyone's way of life. IUPAC Presidents are elected by

8554-510: Was decided that the journal would reprint old journal editions to keep all chemistry knowledge available. The Compendium of Chemical Terminology , also known as the "Gold Book", was originally worked on by Victor Gold . This book is a collection of names and terms already discussed in Pure and Applied Chemistry . The Compendium of Chemical Terminology was first published in 1987. The first edition of this book contains no original material, but

8648-644: Was established in 1919 as the successor of the International Congress of Applied Chemistry for the advancement of chemistry . Its members, the National Adhering Organizations, can be national chemistry societies , national academies of sciences , or other bodies representing chemists. There are fifty-four National Adhering Organizations and three Associate National Adhering Organizations. IUPAC's Inter-divisional Committee on Nomenclature and Symbols ( IUPAC nomenclature )

8742-537: Was first suggested at the Paris IUPAC Meeting of 1957. During this meeting the commercial publisher of the journal was discussed and decided on. In 1959, the IUPAC Pure and Applied Chemistry Editorial Advisory Board was created and put in charge of the journal. The idea of one journal being a definitive place for a vast amount of chemistry was difficult for the committee to grasp at first. However, it

8836-417: Was mentioned earlier that the dimensions have different band structure and spectroscopy. For non-metallic solids, which are one dimensional, have optical properties that are dependent on the electronic transitions between valence and conduction bands. In addition, the spectroscopic transition probability is between the initial and final orbital and it depends on the integral. φ i is the initial orbital, φ f

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