GaAs
- Practical Electron Microscopy and Database -
- An Online Book -

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Figure 2084 shows bandgap and chemical bond length for semiconductors used in visible LEDs (light emitting devices).

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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