ELECTRON-MOBILITY IN INAS1-XSBX AND THE EFFECT OF ALLOY SCATTERING

The significance of alloy scattering on the electron mobility of InAs(1-x)Sb(x) is studied in detail. Since little experimental data are available for the InAs(1-x)Sb(x) compound, calculations of the electron mobility of the binary InAs and InSb semiconductors are first evaluated from the average momentum relaxation times, (tau-m) of the individual mechanisms (comprising ionized and neutral impurities, acoustic phonon deformation potential and piezoelectric, optical phonon deformation potential and polar) so that they can be compared to available experimental results. Having ensured that the calculated data are in good agreement with the experimental results in these binary compounds, the electron mobility of the ternary, InAs(1-x)Sb(x) as a function of x at 77 K and 300 K is calculated by introducing an alloy scattering term. At 77 K, for a total doping concentration of approximately equals 10(17) cm-3, the electron mobility of InAs1-xSbx is limited by ionized impurity scattering and alloy scattering is insignificant. However, for doping concentration of approximately equals 10(15) cm-3, alloy scattering is found to be the most significant process from about x = 0.1 to 0.8. At 300 K the alloy scattering reduces the total electron mobility from between a few percent at x = 0.15 to a maximum of about 11% for x = 0.60. It is observed that alloy scattering is greatest at x = 0.15 but it still is about 11% of the total electron mobility at this composition. The alloy mobilities at 77 K for x = 0.6 and x = 0.15 are 1.28 X 10(6) cm2 V-1s-1 and 7.96 X 10(5) cm2 V-1s-1, respectively. The mobilities at x = 0.60 are further evaluated as a function of the doping carrier concentration at 77 and 300 K. It is found that alloy scattering becomes increasingly significant for lightly doped semiconductors at low temperatures.