Nomenclature
CAS number: 1303-00-0
AsGa; mol wt 144.64.
As 51.80%, Ga 48.20%.
GaAs.
Description and references
Prepd by passing a mixture of hydrogen and
arsenic vapor over gallium(III) oxide at 600°: Goldschmidt, Skr. Akad. Oslo 1926, no. 8, pp
34, 100; Ber. 60, 1289
(1927). Simplified procedure: Juza, Schulz, Z. Anorg. Allg. Chem. 275, 65 (1954); Minden, Sylvania Technol. 11, no. 1, p
19 (Jan. 1958). Vapor phase crystal growth: McAleer et al., J. Electrochem. Soc. 108, 1168 (1961). Use in high-speed microcircuits: A. L. Robinson, Science 219, 275 (1983). Review
of toxicology and human exposure: Toxicological
Profile for Arsenic (PB2000-108021, 2000) 468 pp.
Properties
Cubic crystals. mp 1238°. Dark gray with metallic sheen. Hardness
4.5. d425 5.31. Thermal expansion coefficient: 5.9×106. Thermal conductivity 0.52 watt units. Specific heat 0.086 cal/g/°C.
Molten gallium arsenide attacks quartz, therefore graphite boats
or quartz boats, which are carbon coated by pyrolytic decompn of methane,
should be used in zone refining. GaAs single crystals have been grown
by the Czochralski technique and by the floating zone method. Extensive
twinning occurs. Intrinsic electron concn 107. Energy
gap at room temp 1.38 electron volts. Electron mobility 8800 cm2/volt sec. Hole mobility 450 cm2/volt sec. Effective
mass for electrons 0.06 m0. Lattice constant
5.654. Dielectric constant 11.1. Intrinsic resistivity at 300 K
= 3.7×108 ohm-cm. Electron lattice mobility at 300 K =
10,000 cm2/volt-sec. Intrinsic charge density at 300 K
= 1.4×106/cm3. Electron diffusion constant
at 300 K = 310 cm2/sec. Hole diffusion constant = 11.5
cm2/sec.Use
In semiconductor applications (transistors, solar
cells, lasers).