NSM Archive - Gallium Arsenide (GaAs) - Mechanical properties, elastic constants, lattice vibrations

AlGaAs - Aluminium Gallium Arsenide

Mechanical properties, elastic constants, lattice vibrations

Basic Parameter
Elastic constants
Acoustic Wave Speeds
Phonon frequencies

Basic Parameter

Bulk modulus (7.55+0.26x)·1011 dyn cm-2
Density 5.32-1.56x g cm-3
Hardness on the Mohs scale ~ 5
Cleavage plane {110}
Piezoelectric constant e14= -0.16-0.065x C m-2

Elastic constants 300 K.

C11=(11.88+0.14x)·1011 dyn/cm2
C12=(5.38+0.32x)·1011 dyn/cm2
C44=(5.94-0.05x)·1011 dyn/cm2
(Adachi [1985]).

For T = 300 K

Bulk modulus (compressibility-1) Bs= =(7.55+0.26x)·1011dyn/cm2
Anizotropy factor A=0.55-0.01x
Shear modulus C'=(3.25-0.09x)·1011dyn/cm2
[100] Young's modulus Yo=(8.53-0.18x)·1011dyn/cm2
[100] Poisson ratio σo=(0.31+0.1x)
(Adachi [1985]).

Acoustic Wave Speeds

Wave
propagation
Direction		 Wave
character		 Expression for wave speed Wave speed
(in units of
105 cm/s)
[100] VL (C11/ρ )1/2 4.73+0.68x+0.24x2
VT (C44/ρ )1/2 3.34+0.46x+0.16x2
[110] Vl [(C11+C12+2C44)/2ρ ]1/2 5.24+0.78x+0.24x2
Vt|| Vt||=VT=(C44/ρ)1/2 3.34+0.46x+0.16x2
Vt⊥ [(C11-C12)/2ρ]1/2 2.47+0.33x+0.10x2
[111] Vl' [(C11+2C12+4C44)/3ρ]1/2 5.40+0.79x+0.26x2
Vt' [(C11-C12+C44)/3ρ]1/2 2.79+0.38x+0.12x2

Phonon frequencies

Optical phonon energy as a function of x.
The compositional dependence of the effective phonon energy <ωL0> and <ωT0> are shown by the dashed lines.
(Adachi [1985]).