Indium gallium arsenide

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Indium gallium arsenide (InGaAs), also known as gallium indium arsenide , is a semiconductor material and the name for a group of alloys made from the two basic materials indium arsenide (InAs) and gallium arsenide (GaAs). The alloy is one of the III-V compound semiconductors and is used as a direct semiconductor in the field of optoelectronics .

General

Band gap curve as a function of the mixing ratio X of indium and gallium arsenide

Depending on the mixing ratio of the two starting substances, a notation of the form In 1− X Ga X As is used, where X indicates the mixing ratio, the optical properties can be changed during the production of the material by changing the band gap , as shown in the adjacent Figure shown. With the value X = 0.47, indium gallium arsenide is commercially available under the CAS number 106097-59-0, but any other mixing ratio can be produced. With X = 0 it is pure indium arsenide with a band gap of 0.34  eV at 300 K to X = 1 for pure gallium arsenide with a band gap of 1.42 eV.

Commercially available indium gallium arsenide with a mixing ratio of X = 0.47 is grown as a single crystal by means of crystal growth on a substrate of indium phosphide (InP). The ratio results from the fact that in this case the lattice constant of the indium gallium arsenide alloy corresponds to that of indium phosphide. The band gap of In 0.53 Ga 0.47 As is 0.75 eV; the alloy has a high electron mobility of almost 10,000 cm 2 · V −1 · s −1 .

Applications

The primary area of ​​application are infrared detectors such as photodiodes , with maximum sensitivity as a function of the wavelength in the range from 1.1 µm to 1.7 µm. In contrast to similar semiconductor materials such as germanium , which also has a high sensitivity in the infrared range, indium gallium arsenide has a smaller dark current and a faster response time with the same detector size . The first photodiodes based on indium gallium arsenide were developed in 1977 by TP Pearsall and RW Hopson at Cornell University , New York .

Due to the high electron mobility, other applications of the material are in so-called high-electron-mobility transistors (HEMT). With a transit frequency of over 600 GHz, transistors made of indium gallium arsenide are among the fastest transistors with applications in the field of terahertz radiation .

Individual evidence

  1. ^ John C. Woolley, Mathew B. Thomas, Alan G. Thompson: Optical energy gap variation in Ga x In 1 − x As alloys. In: Canadian Journal of Physics. 46, No. 2, 1968, pp. 157-159, doi : 10.1139 / p68-023
  2. ↑ a b T.P. Pearsall: Ga 0.47 In 0.53 As: A ternary semiconductor for photodetector applications. In: IEEE Journal of Quantum Electronics. Volume 16, Number 7, 1980, pp. 709-720, doi : 10.1109 / JQE.1980.1070557
  3. ^ TP Pearsall, MA Pollack: Chapter 2 - Compound Semiconductor Photodiodes. In: WT Tsang (Ed.): Semiconductors and Semimetals. Volume 22D, Academic Press, New York 1985, ISBN 0-12-752153-4 , pp. 174-241.
  4. ↑ TP Pearsall, RW Hopson Jr .: Growth and characterization of lattice-matched epitaxial films of Ga x In 1 − x As / InP by liquid-phase epitaxy. In Journal of Electronic Materials. 7, No. 1, 1978, pp. 133-146, doi : 10.1007 / BF02656025 .
  5. ^ Arnulf Leuther: Towards Terahertz Circuits - On the way to the Terahertz circuit . In: Annual report Fraunhofer Institute for Applied Solid State Physics . 2010 ( PDF [accessed October 8, 2013]).