Effect of surface treatments on the electrical and optical properties of CdZnTe single crystal

The effects of surface treatments on the electrical and optical properties of CdZnTe (CZT) crystals were studied experimentally. The IR transmittance of CZT after cutting is only 15%, after chemically polishing with Br-MeOH it increased to 63%. The reflection of surface roughness and absorption of surface-damaged layer should be responsible for the variation. After aging and passivation,CZT possesses low IR transmittance. After fine polishing, the surface oxide layer was removed and the IR transmittance increased. CZT wafers with high roughness possess low surface sheet resistance, and the Te enrichment introduced by etching with Br-MeOH results in high surface leakage current. The effects of etching and passivation on surface trap state have been analyzed with photoluminescence spectra. Etching can deprive effectively the surface damage layer, and passivation can minimize the surface trap state density.