THE IMPACT OF OXYGEN INLET DURING CLOSE-SPACED SUBLIMATION PROCESS ON THE AS-DEPOSITED AND CHLORINE TREATED MICROSTRUCTURE OF CDTE LAYERS

摘要

In this study CdTe thin films were deposited by close-spaced sublimation (CSS) in an oxygen ambient and the influence of oxygen on the properties of as-deposited and chlorine activated CdTe microstructures were investigated. FE-SEM imaging of ion-polished cross sections of the as-deposited CdTe-layers revealed a significant change from a block-like to a columnar microstructure with increasing oxygen concentration in the gas flux. After the chlorine activation step at 440 °C the oxygen free sample shows a strong sulfur diffusion whereas samples with low oxygen inlet show a suppressed diffusion. Due to the enlarged amount of grain boundaries in the as-deposited microstructure the sulfur diffusion became stronger again with increasing oxygen concentration.