Effect of alloy scattering on the magnetotransport in narrowgap semiconductors at low temperature

Magnetotransport in narrow band-gap semiconductors at low temperature in the presence of a quantising magnetic field has been theoretically investigated assuming electron scattering by acoustic phonons, ionized impurities and alloy disorder. The model includes band nonparabolicity, free carrier screening and nonequipartition of acoustic phonons. It is seen that the low field longitudinal mobility in n-Hg_0.8Cd_0.2Te in the extreme quantum limit (EQL) at 4.2 K is totally governed by the scattering of carriers due to the alloy disorder potential. The total effect of all such scattering mechanisms is close to that where the alloy disorder scattering is considered alone. However, at microwave frequencies both the real and imaginary parts of the mobility decrease with increase in frequency above 1 GHz. Longitudinal drift velocity in the high field regime has also been investigated in the EQL to study the effect of alloy scattering reducing the hot electron longitudinal drift velocity