3.5 Velocity Saturation

The temperature dependence of the saturation velocities of electrons and holes in basic materials is calculated by

$$v^{\mathrm{sat}}_{\nu} = \frac{v^{\mathrm{sat}}_{\nu,300}}{1... ...laystyle{\left(\frac{T_{\mathrm{L}}}{\mathrm{300 K}}\right)}}$$ (3.134)

The following model parameters from [182] are used.

Table 3.31: Parameter values for velocity saturation model

Material	$v^{\mathrm{sat}}_{n,300}$ [m/s]	$A_{n}$	$v^{\mathrm{sat}}_{p,300}$ [m/s]	$A_{p}$
Si	1.0e5	0.26	0.704e5	0.63
Ge	0.7e5	0.55	0.63e5	0.61
GaAs	0.72e5	0.56	0.9e5	0.41
AlAs	0.85e5	0.55	0.8e5	0.3
InAs	0.9e5	0.57	0.5e5	0.3
InP	0.67e5	0.68	0.5e5	0.3
GaP	0.88e5	0.30	0.5e5	0.3

In the case of alloy materials the temperature dependent saturation velocities are calculated first using (3.134). For an alloy $\mathrm {A}_{1-x}\mathrm {B}_x$ the model suggests a quadratic interpolation between the saturation velocities for electrons of the basic materials (A and B) depending on the material composition $x$. In case of holes a linear interpolation is assumed.

$$v_{\nu}^\mathrm {AB}= v_{\nu}^\mathrm {A}\cdot(1-x) + v_{\nu}^\mathrm {B}\cdot x + C_{v,\nu}\cdot(1-x)\cdot x$$ (3.135)

The bowing parameters $C_{v,n}$ and $C_{v,p}$ are summarized in the following table.

Table 3.32: Parameter values for velocity saturation model for alloy materials

Material	$C_{v,n}$[m/s]	$C_{v,p}$[m/s]
SiGe	-2.28e5	0.0
AlGaAs	-0.0512e5	0.0
InGaAs	-0.196e5	0.0
InAlAs	-2.13e5	0.0
InAsP	0.0	0.0
GaAsP	0.0	0.0
InGaP	-0.3e5	0.0