The surface passivation of Cd1-xZnxTe as to ZnS thickness and pre-heating

Abstract

The dielectric material of ZnS is used for the surface passivation of the CdZnTe. The surface morphology and the optical property of ZnS/CdZnTe structure according to variation of ZnS thickness is analyzed by AFM and low temperature photoluminescence (PL) measurement, respectively. As the results, it shows that the change of PL spectra of CdZnTe as to ZnS thickness indicates the significant alteration of electronic states near the interface of ZnS/CdZnTe. From the result of improvement for optical property of CdZnTe at ZnS thickness of 200 nm, it is known that the thickness is an essential condition for the passivation of CdZnTe. Also, the measurement of C-V for the MIS structure of Au/ZnS/CdZnTe is done to study the interface trap state of ZnS/ CdZnTe structure as to pre-heating of CdZnTe. Therefore, it is shown that the pre-heating of CdZnTe is an essential process of the passivation in order to reduce the trap state. Seventy-seven Kelvin PL measurement is studied for the pre-heating condition of the CdZnTe surface. It is known that the optimum condition of pre-heating temperature and time is 200 degrees C and 60 min, respectively. And the result of I-V measurement shows that the surface leakage current of CdZnTe is considerably reduced after the passivation of ZnS with these conditions. It means that the electronic property of the interface should be improved after the passivation process.