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Figure 2084 shows bandgap and chemical bond length for semiconductors used in visible LEDs (light emitting devices).
Figure 2084. Bandgap and chemical bond length for semiconductors used in visible LEDs (light emitting devices). Adapted from [1]
Note that GaAs has poor native oxides.
Crystalline Si has the space group of Fd-3m (see in Table 2019) and the space group for GaAs and InP is F-43m. Both these space groups are simple face-centred cubic (fcc) lattices.
Table 2084a. Properties of GaAs crystals.
Energy Gap Eg (eV) |
1.424 at 300 K; 1.52 at 0 K |
|
Intrinsic resistivity ρi (Ωcm) |
3.3 x 108 |
Intrinsic carrier concentration ni (cm-3) |
2.1 x 106 |
Electron mobility µe (cm2V-1s-1) |
≤8500 |
Hole mobility µh (cm2V-1s-1) |
≤400 |
Dielectric constant |
12.9 |
Heavy hole mass |
0.51 |
Light hole mass |
0.082 |
Lattice constant (nm) |
0.5653 |
Density at 300K (g/cm3) |
5.318 |
Optical phonon energy (meV) |
36 |
Conduction band minimum |
Γ |
Energy gap at Γ (eV) |
1.42 |
Spin–orbit splitting (eV) |
0.341 |
Electron affinity (eV) |
4.07 |
Electron drift
mobility µe
(m2V-1s-1) |
0.85 at 300 K |
Hole drift
mobility µh
(m2V-1s-1) |
0.04 at 300 K |
Static refractive index |
3.3 |
Radiative recombination coefficient
(cm3s−1) |
7 × 10−14 |
Elastic constant (dyn cm-2) |
C11= 11.9 ×10−11 at 300 K; C12= 5.34 ×10−11 at 300 K; C44= 5.96 ×10−11 at 300 K |
Melting temperature (K) |
1513 |
Electron mass |
0.063 |
Table 2084b. Some surface energies (J/m2) of low-index surfaces of GaAs crystals. The types of reconstructions are indicated. (1x1) relaxed denotes an unreconstructed cleavage surface.
Solid |
(100)
|
(110)
|
(111) |
GaAs |
0.96 β2(2 × 4) |
0.83 (1 × 1) relaxed |
0.87 (2 x 2) Ga vacancy |
[1] Ponce, F. A. and Bour, D.P., Nature, 386, (1997) 351.
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