Characteristics of the dislocations in CdZnTe crystals revealed by etch pits

The configurations and distributions of triangular pyramid etch pits on the (1 1 1)B face of CdZnTe revealed by Everson etch were studied using a scanning electron microscope (SEM), an optical microscope and a confocal laser scanning microscope (CLSM). Six types of triangular pyramid etch pits with different configurations were observed, one for the first time. These etch pits correspond to threading dislocations in the materials. By measuring the depths and orientations of the pit tips as well as the side lengths of the triangular pits on the surface, the orientations of the dislocations were determined. They are 〈2̄ 1̄ 1〉, 〈1̄ 3̄ 1̄〉, 〈1̄ 1̄ 1〉, 〈1 5̄ 1〉, 〈0 3̄ 1〉 and 〈1̄ 1̄ 0〉 for the six types of triangular pyramid etch pits. Among them, dislocations with 〈2̄ 1̄ 1〉, 〈1̄ 1̄ 1〉, 〈1 5̄ 1〉 and 〈0 3̄ 1〉 orientations have higher densities in CdZnTe materials. It was also found that the proportion of triangular pyramid etch pit to total etch pits is variable for different CdZnTe wafers and related to the stoichiometry of CdZnTe melt. These results show that Everson etch can reveal more information of CdZnTe materials than etch pit density (EPD).