Effect of low-temperature annealing on electrical properties of n-HgCdTe

The effect of low-temperature isothermal annealing on electrical properties of CdxHg1−xTe (mercury cadmium telluride, MCT) films is investigated. Films of n-type conduction with x=0.21–0.23 were grown on GaAs substrates by MBE. Annealings of 1–1000 h duration were carried out at 90–230°C. The changes in conductivity, the Hall factor, and the lifetime of minority carriers after annealing are explained by the formation of mercury vacancies and egress of Hg atoms from the sample. The effect of various surface coatings on the rate of variation of MCT film electrical properties was investigated. An anodic oxide appeared to be the most efficient coating to stabilize the parameters of n-type films. The analysis of the magnetic-field dependences of the Hall factor and conductivity has shown that the observed modification of parameters upon annealing can be described in terms of a two-layer model with two types of electrons—high and low mobility.