THE EFFECT OF CARRIER DENSITIES AND COMPENSATION RATIOS ON THE ELECTRON-MOBILITY OF INASXP1-X

The electron mobility of InAsxP1-x has been calculated for an ionized impurity concentration between 10(14) cm-3 and 2 x 10(17) cm-3 at 300 K and 77 K by using Matthiesson rule formalism and the variational method. These results are shown to be in reasonably good agreement with experimental mobilities. The electron mobilities of InAs0.13P0.87, InAs0.5P0.5, and InAs0.80P0.20 with temperature are also calculated for a range of ionized impurity concentration. Since the compensation ratio of acceptor and donor doped impurities, the inhomogeneity of the samples and other effects are not taken into account, these results represent the upper theoretical limit of electron mobility in InAsxP1-x. The dependence of electron mobility of InAsxP1-x on carrier concentration and compensation ratio are also studied for these alloys. The compensation ratio does not have a significant effect on mobility at room temperature, particularly for low carrier density where ionized impurities are relatively unimportant, while at 77 K, the effect of compensation is very significant. The upper theoretical electron mobilities for x = 0.13, 0.5 and 0.8 are 4500, 6500 and 13,000 cm2 V-1 s-1 at 300 K and 50,000, 50,000 and 150,000 cm2 V-1 s-1 at 77 K, respectively. The various accepted methods used in the calculation of electron mobility are briefly discussed.