The change of Au-ZnS and Au-CdS diode structure parameters caused by low-dose X-ray irradiation

The effect of the low dose X-ray irradiation (Cu K-alpha, 20-40 kV, 20-40 mu A) on physical parameters of Au-ZnS and Au-CdS surface-barrier structure was studied and the results are presented in this paper. The physical parameters of contacts (the height of potential barrier, the profiles of doped impurity distribution in depth, the density distribution of surface states (SS) in a forbidden band) were determined by analysing of I-V and highfrequency C-V characteristics analyzing. The spectra and kinetic parameters of deep level (DL) in a forbidden band were studied by means of capacity modulation spectroscopy method. The concentration of donor traps and effective density of SS reaches the saturation at irradiation doses higher than 3 C/kg in Au-CdS case. It is connected with migration of defects from semiconductor volume into near surface region of Au-CdS contact. The observed, after irradiation DL kinetic parameter changes in ZnS and their profiles of concentration distribution, changes in depth may be explained by radiation-stimulated decrease of Au-ZnS SS effective density contact, i.g. decrease of recharging SS distortion influences on the mentioned DL parameters.