THE MAJORITY CARRIER MOBILITY OF N-TYPE AND P-TYPE HG0.78CD0.22TE LIQUID-PHASE EPITAXIAL-FILMS AT 77-K

The dependence of majority carrier mobility on carrier concentration at 77 K in Hg0.78Cd0.22Te has been studied by Hall measurements on about 190 n-type and 360 p-type liquid phase epitaxial films. The n-type films were indium doped with the carrier concentration varying from 1 x 10(14) to 2 x 10(16) cm-3. The measured electron mobility changed from 2 x 10(5) to 8 x 10(4) cm2/V s. The p-type films were undoped (Hg vacancy) with the carrier concentration varying from 2 x 10(15) to 3 x 10(17) cm-3. The measured hole mobility changed from 600 to 200 cm2/V s. By comparing calculated mobility curves with the experimental data, we found that the major scattering mechanisms for electron mobility in n-type materials were polar optical phonon, ionized impurity, and alloy disorder scatterings. These three scattering mechanisms also dominate the hole mobility in p-type materials at 77 K. It was also found that a model with Hg vacancy as doubly ionized shallow acceptors fitted very well the hole mobility versus carrier concentration data.