Effect of surface damaged layers on the electronic properties of Hg_1-xMn_xTe wafers

Electronic properties of several Hg_1-xMn_xTe wafers before and after chemical polish were characterized by Van Der Pauw method at 77 K. Results showed that values of resistivity and Hall coefficient of the wafers before etching are lower than those after etching, while Hall mobility and carrier density were higher. The maximum of resistivity decreased by 25%, the maximum of Hall mobility increased by 31%, but Hall coefficient and carrier density changed only by about 2% before and after etching. There existed a lot of dislocations in surface damaged layer, resulting in the decrease of Hall mobility of charge carrier, but the values of Hall mobility of wafers before chemical polish were higher, the minimum of which increased by 21%. It is a abnormal phenomena. All the experimental results can be explained using a three-layer model.