A STUDY OF POLYCRYSTALLINE CD(ZN, MN)TE/CDS FILMS AND INTERFACES

Polycrystalline films of Cd1-x Zn x Te (x = 0-0.4) and Cd1-x Mn x Te (x = 0-0.25) were grown by MBE and MOCVD, respectively, on CdS/SnO2/glass substrates to investigate their feasibility for solar cell applications. The compositional uniformity and interface quality of the films were analyzed by x-ray diffraction, surface photovoltage, and Auger depth profile measurements to establish a correlation between growth conditions and lattice constant, atomic concentration, and bandgap of the ternary films. MBE-grown polycrystalline Cd1-x Zn x Te films showed a linear dependence between Zn/(Cd + Zn) beam flux ratio, Zn concentration in the film, and the bandgap. Polycrystalline Cd1-x Zn x Te films grown at 300° C showed good compositional uniformity in contrast to compositionally non-uniform Cd1-x Mn x Te films grown by MOCVD in the temperature range of 420-450° C. The MBE-grown Cd1-x Zn x Te interface also showed significantly less interdiffusion compared to the MOCVD-grown Cd1-x Mn x Te/CdS interface, where preferential exchange between Cd from the CdS layer and Mn from the Cd1-x Mn x Te film was observed. The compositional uniformity of MOCVD-grown polycrystalline Cd1-x Mn x Te films grown on CdS/SnO2/glass substrates was found to be a strong function of the growth conditions as well as the Mn source. © 1990 The Minerals, Metals and Materials Society.