Surface passivation process of the wafers for CdZnTe detector

The influences of surface passivation process on the properties of the wafers for CdZnTe (CZT) detector were reported. Firstly, the CZT wafers were polished mechanically and chemically by means of metallographic abrasive papers and chemical etchant. Then the wafers were passivated respectively by H2O2 solution and NH4F/H2O2 solution. By using micro-current test instrument and scanning electron microscopy (SEM), the influences of different passivation time on the electronic properties of the wafers were studied. It was found that when CZT wafers were passivated 30 minutes with NH4F/H2O2 solution, there formed a high resistivity layer of oxide on the surface. The leakage current of the surface is the lowest, resistivity of the crystal heightened for 1-2 order of magnitude, up to 109-10 Ω · cm. The wafers can be used for the preparation of CZT detectors.