Selective etching of ZnTe in HF:H₂O₂:H₂O solution: Interpretation of extended defect-related etch figures

HF:H₂O₂:H₂O solution (40%wt.HF: 30wt.%H₂O₂: H₂O, 3:2:1 by volume) was used to reveal extended defects (line, face and volume defects) in bulk ZnTe crystals grown from Te solution. The etch patterns were analyzed based on their size, shape and distribution. The etch figures, both in the shape of pits and hillocks with high resolution, show forms controlled by the symmetries of the respective faces were produced. Two different sizes of pits were observed, the larger-size pits correspond to dislocations penetrating the surface, however, the smaller-size texture pits are produced on the defect-free region, which serve as standard pits on respect faces. The face defects, such as grain boundaries, sub-grain boundaries, dislocation walls, twins and stacking faults, can be all displayed clearly. Another essential feature of the etchant is that, it can effectively dissolve Te-rich phase (Te inclusion/precipitates), which makes it promising to reveal the shape of this volume defect. 40%wt.HF:30wt.%H₂O₂:H₂O (3:2:1 by volume) solution shows strong orientation and phase selectivity, it is also very sensitive to impurity decorated defects, thus can effectively reveal various extended defects (line, face and volume defects) of ZnTe crystals. In addition, smaller size texture pits are also produced on the defect-free regions, which serve as reference standard pits during the analysis of defect-related etch figures.