Characterization of Zn Composition in Cd_(1-x) Zn_x Te by Room Temperature Micro-Photoluminescence Mapping

The study of nominal Cd 0.96 Zn 0.04 Te (CZT) wafer by micro photoluminescence (μ PL)mapping is presented.The PL mapping is performed in 19μm×16μm defect containing area in micrometer scale and 7 9mm×6 0mm large area in millimeter scale,respectively.Each PL spectrum has been fitted theoretically,resulting in the energy band gap E g . The maps of E g are drawn for each measurement,with the Zn composition distributions.The statistics proves the inhomogeneity in composition,which can be interpreted in terms of surface defects and stress.After Br/methanol polishing on the wafer,two similar measurements were carried out and the results show a great improvement in E g homogeneity and the deduced Zn composition is close to the real one.This improvement is due to the elimination of the surface defects and the induced stress.It suggests the feasibility of PL mapping in determining the Zn composition homogeneity and distribution in CZT wafer.