LONGITUDINAL DIFFUSIVITY IN N-TYPE HG0.8CD0.2TE IN THE EXTREME QUANTUM LIMIT - EFFECT OF ALLOY SCATTERING

A theoretical model is proposed to study the effect of alloy scatterin g on the hot electron longitudinal diffusivity in n-type Hg0.8Cd0.2Te in the extreme quantum limit, at a temperature of 4.2 K, assuming that the electron-electron interaction is strong enough to maintain a disp laced Maxwellian distribution. It is seen that diffusivity increases w ith increase in electric field for all the scattering mechanisms, viz. , ionized impurity scattering, alloy disorder, and polar-optic-phonon scatterings. Unlike in low-field transport where alloy disorder scatte ring is the most dominant mechanism, here polar-optic-phonon scatterin g is the most effective one. The effects of band hyperbolicity and fre e-carrier screening have also been examined. It is seen that when band hyparabolicity and quantum screening are included in the model, the t heoretical value of the longitudinal diffusivity decreases.