SURFACE-PROPERTIES OF P-HG1-XCDXTE

Electrical conductivity sigma and Hall coefficient R(H) have been measured in p-Hg1-xCd(x)Te crystals with x almost-equal-to 0.2 in the temperature region 4.2-300 K. The influence of a crystal surface on galvanomagnetic properties is observed only in the temperature region T < 20 K. Both positive and negative charges are formed on the surface under the influence of a natural air atmosphere after etching in BrMeOH. The formation of an accumulation layer on p-HgCdTe has been observed for the first time. The growth of an inversion layer was studied over one year after etching. The concentration of surface electrons reached the value 3.5 x 10(12) cm-2. In the accumulation layer, the hole surface concentration rapidly increased within two months from 10(13) cm-2 to 10(14) cm-2. The bending of the bands has been calculated, first, by a classical method of solving the Poisson equation and second, by a quantum method using the Zawadski model of a triangular asymmetrical potential well. Preliminary study shows that the type of layer created, inversion or accumulation, can be connected with the orientation of the surface.