Electron Mobility in Hg1−xCdxTe

The electron mobility in Hg1−xCdxTe has been obtained from Hall and resistivity measurements for x as high as 0.6, and in samples with carrier concentrations generally less than 2×1015/cm3. The room-temperature mobility was found to increase uniformly, as x was varied from CdTe, to a maximum value at the semiconductor-semimetal transition. With further reduction in x the mobility drops uniformly again to the HgTe value. Estimates are made of the contributions of various scattering mechanisms to the room-temperature mobility. The effects of optical-mode scattering were calculated for a nondegenerate parabolic band and were the right order of magnitude for compositions as low as x=0.20, but failed to fit the measured results accurately. The ionized impurity scattering mobility was also calculated, and the model of singly ionized donor scattering centers accounts very well for the low-temperature mobility. The results indicate that n-type Hg1−xCdxTe is not compensated to any large extent over a large range in compositions.