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AlGaInP
Aluminium gallium indium phosphide (, also AlInGaP, InGaAlP, etc.) is a semiconductor material that provides a platform for the development of multi-junction photovoltaics and optoelectronic devices. It has a direct bandgap ranging from ultraviolet to infrared photon energies. AlGaInP is used in heterostructures for high-brightness red, orange, green, and yellow light-emitting diodes. It is also used to make diode lasers. Preparation AlGaInP is typically grown by heteroepitaxy on gallium arsenide or gallium phosphide substrates in order to form a quantum well structure that can be fabricated into different devices. Properties The direct bandgap of AlGaInP encompasses the energy range of visible light (1.7 eV - 3.1 eV). By selecting a specific composition of AlGaInP, the bandgap can be selected to correspond to the energy of a specific wavelength of visible light. For instance, this can be used to obtain LEDs that emit red, orange, or yellow light. Like most other II ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Light-emitting Diode
A light-emitting diode (LED) is a semiconductor device that emits light when current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons. The color of the light (corresponding to the energy of the photons) is determined by the energy required for electrons to cross the band gap of the semiconductor. White light is obtained by using multiple semiconductors or a layer of light-emitting phosphor on the semiconductor device. Appearing as practical electronic components in 1962, the earliest LEDs emitted low-intensity infrared (IR) light. Infrared LEDs are used in remote-control circuits, such as those used with a wide variety of consumer electronics. The first visible-light LEDs were of low intensity and limited to red. Early LEDs were often used as indicator lamps, replacing small incandescent bulbs, and in seven-segment displays. Later developments produced LEDs available in visible, ultraviolet (U ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diode Laser
The laser diode chip removed and placed on the eye of a needle for scale A laser diode (LD, also injection laser diode or ILD or semiconductor laser or diode laser) is a semiconductor device similar to a light-emitting diode in which a diode pumped directly with electrical current can create lasing conditions at the diode's junction. Driven by voltage, the doped p–n-transition allows for recombination of an electron with a hole. Due to the drop of the electron from a higher energy level to a lower one, radiation is generated in the form of an emitted photon. This is spontaneous emission. Stimulated emission can be produced when the process is continued and further generates light with the same phase, coherence, and wavelength. The choice of the semiconductor material determines the wavelength of the emitted beam, which in today's laser diodes range from the infrared (IR) to the ultraviolet (UV) spectra. Laser diodes are the most common type of lasers produced, with a wide ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
III-V Semiconductors
Semiconductor materials are nominally small band gap insulators. The defining property of a semiconductor material is that it can be compromised by doping it with impurities that alter its electronic properties in a controllable way. Because of their application in the computer and photovoltaic industry—in devices such as transistors, lasers, and solar cells—the search for new semiconductor materials and the improvement of existing materials is an important field of study in materials science. Most commonly used semiconductor materials are crystalline inorganic solids. These materials are classified according to the periodic table groups of their constituent atoms. Different semiconductor materials differ in their properties. Thus, in comparison with silicon, compound semiconductors have both advantages and disadvantages. For example, gallium arsenide (GaAs) has six times higher electron mobility than silicon, which allows faster operation; wider band gap, which allows op ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trimethylgallium
Trimethylgallium, often abbreviated to TMG or TMGa, is the organogallium compound with the formula Ga(CH3)3. It is a colorless, pyrophoric liquid. Unlike trimethylaluminium, TMG adopts a monomeric structure. When examined in detail, the monomeric units are clearly linked by multiple weak Ga---C interactions, reminiscent of the situation for trimethylindium. Preparation Two forms of TMG are typically investigated: Lewis base adducts or TMG itself. All are prepared by reactions of gallium trichloride with various methylating agents. When the methylation is conducted with methylmagnesium iodide in diethyl ether, the product is the poorly volatile diethyl ether adduct. As noted by TMG discoverers Kraus and Toonder in 1933, the ether ligand is not readily lost, although it may be displaced with liquid ammonia. When the alkylation is conducted with methyl lithium in the presence of a tertiary phosphine the air-stable phosphine adduct is obtained: : Heating the solid phosphin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trimethylindium
Trimethylindium, often abbreviated to TMI or TMIn, is the organoindium compound with the formula In(CH3)3. It is a colorless, pyrophoric solid. Unlike trimethylaluminium, but akin to trimethylgallium, TMI is monomeric. Preparation TMI is prepared by the reaction of indium trichloride with methyl lithium. : InCl3 + 3LiMe → Me3In.OEt2 + 3LiCl Properties Compared to trimethylaluminium and trimethylgallium, InMe3 is a weaker Lewis acid. It forms adducts with secondary amines and phosphines. A complex with the heterocyclic triazine ligand (PriNCH2)3 forms a complex with 6-coordinate In, where the C-In-C angles are 114°-117° with three long bonds to the tridentate ligand with N-In-N angles of 48.6° and long In-N bonds of 278 pm. Structure In the gaseous state InMe3 is monomeric, with a trigonal planar structure, and in benzene solution it is tetrameric.''CVD of compound semiconductors, Precursor Synthesis, Development and Applications'', Anthony C. Jones, Paul O'Brien, Jo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MOVPE
Metalorganic vapour-phase epitaxy (MOVPE), also known as organometallic vapour-phase epitaxy (OMVPE) or metalorganic chemical vapour deposition (MOCVD), is a chemical vapour deposition method used to produce single- or polycrystalline thin films. It is a process for growing crystalline layers to create complex semiconductor multilayer structures. In contrast to molecular-beam epitaxy (MBE), the growth of crystals is by chemical reaction and not physical deposition. This takes place not in vacuum, but from the gas phase at moderate pressures (10 to 760 Torr). As such, this technique is preferred for the formation of devices incorporating thermodynamically metastable alloys, and it has become a major process in the manufacture of optoelectronics, such as light-emitting diodes, its most widespread application. It was first demonstrated in 1967 at North American Aviation (later Rockwell International) Autonetics Division in Anaheim CA by Harold M. Manasevit. Basic principl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Indium Gallium Phosphide
Indium gallium phosphide (InGaP), also called gallium indium phosphide (GaInP), is a semiconductor composed of indium, gallium and phosphorus. It is used in high-power and high-frequency electronics because of its superior electron velocity with respect to the more common semiconductors silicon and gallium arsenide. It is used mainly in HEMT and HBT structures, but also for the fabrication of high efficiency solar cells used for space applications and, in combination with aluminium ( AlGaInP alloy) to make high brightness LEDs with orange-red, orange, yellow, and green colors. Some semiconductor devices such as EFluor Nanocrystal use InGaP as their core particle. Indium gallium phosphide is a solid solution of indium phosphide and gallium phosphide. Ga0.5In0.5P is a solid solution of special importance, which is almost lattice matched to GaAs. This allows, in combination with (AlxGa1−x)0.5In0.5, the growth of lattice matched quantum wells for red emitting semiconductor las ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heteroepitaxy
Epitaxy (prefix ''epi-'' means "on top of”) is a type of crystal growth or material deposition in which new crystalline layers are formed with one or more well-defined orientations with respect to the crystalline seed layer. The deposited crystalline film is called an epitaxial film or epitaxial layer. The relative orientation(s) of the epitaxial layer to the seed layer is defined in terms of the orientation of the crystal lattice of each material. For most epitaxial growths, the new layer is usually crystalline and each crystallographic domain of the overlayer must have a well-defined orientation relative to the substrate crystal structure. Epitaxy can involve single-crystal structures, although grain-to-grain epitaxy has been observed in granular films. For most technological applications, single-domain epitaxy, which is the growth of an overlayer crystal with one well-defined orientation with respect to the substrate crystal, is preferred. Epitaxy can also play an important ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optical Pumping
Optical pumping is a process in which light is used to raise (or "pump") electrons from a lower energy level in an atom or molecule to a higher one. It is commonly used in laser construction to pump the active laser medium so as to achieve population inversion. The technique was developed by the 1966 Nobel Prize winner Alfred Kastler in the early 1950s. Page 56. Optical pumping is also used to cyclically pump electrons bound within an atom or molecule to a well-defined quantum state. For the simplest case of coherent two-level optical pumping of an atomic species containing a single outer-shell electron, this means that the electron is coherently pumped to a single hyperfine sublevel (labeled m_F\!), which is defined by the polarization of the pump laser along with the quantum selection rules. Upon optical pumping, the atom is said to be ''oriented'' in a specific m_F\! sublevel, however, due to the cyclic nature of optical pumping, the bound electron will actually be unde ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Indium Gallium Arsenide Phosphide
Indium gallium arsenide phosphide () is a quaternary compound semiconductor material, an alloy of gallium arsenide, gallium phosphide, indium arsenide, or indium phosphide. This compound has applications in photonic devices, due to the ability to tailor its band gap via changes in the alloy mole ratios, ''x'' and ''y''. Indium phosphide-based photonic integrated circuits, or PICs, commonly use alloys of to construct quantum wells, waveguides and other photonic structures, lattice matched to an InP substrate, enabling single-crystal epitaxial growth onto InP. Many devices operating in the near-infrared 1.55 μm wavelength window utilize this alloy, and are employed as optical components (such as laser transmitters, photodetectors and modulators) in C-band communications systems. Fraunhofer Institute for Solar Energy Systems ISE reported a triple-junction solar cell utilizing . The cell has very high efficiency of 35.9% (claimed to be a record). See also * Indium gallium ph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aluminium Gallium Phosphide
Aluminium gallium phosphide, , a phosphide of aluminium and gallium, is a semiconductor material. It is an alloy of aluminium phosphide and gallium phosphide. It is used to manufacture light-emitting diode A light-emitting diode (LED) is a semiconductor device that emits light when current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons. The color of the light (corre ...s emitting green light. See also * Aluminium gallium indium phosphide External linksLight-Emitting Diode - An Introduction, Structure, and Applications of LEDs Aluminium compounds Gallium compounds Phosphides III-V semiconductors III-V compounds Zincblende crystal structure {{CMP-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aluminium Compounds
Aluminium (British and IUPAC spellings) or aluminum ( North American spelling) combines characteristics of pre- and post-transition metals. Since it has few available electrons for metallic bonding, like its heavier group 13 congeners, it has the characteristic physical properties of a post-transition metal, with longer-than-expected interatomic distances.Greenwood and Earnshaw, pp. 222–4 Furthermore, as Al3+ is a small and highly charged cation, it is strongly polarizing and aluminium compounds tend towards covalency;Greenwood and Earnshaw, pp. 224–7 this behaviour is similar to that of beryllium (Be2+), an example of a diagonal relationship.Greenwood and Earnshaw, pp. 112–3 However, unlike all other post-transition metals, the underlying core under aluminium's valence shell is that of the preceding noble gas, whereas for gallium and indium it is that of the preceding noble gas plus a filled d-subshell, and for thallium and nihonium it is that of the preceding noble gas plus f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
