STUDY OF CDTE CDS-THIN FILMS BY ISOTOPE-DILUTION, NEUTRON-ACTIVATION ANALYSIS, INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY AND SECONDARY-ION MASS-SPECTROMETRY/

Thin polycrystalline CdTe films can be used as materials for solar cel ls. The CdTe surface is etched with H3PO4/HNO3 solution to remove solu ble Cd compounds and to leave insoluble Te compounds on the surface an d thus creating a layer between CdTe and the electrode material. Diffe rent analytical methods have been used for studying the effect of the etching procedure relating to the electrode deposition on the CdTe sur face. The penetration of phosphorus from the etchant without an intent ional CdTe doping may be beneficial for the thin film structure, Phosp horus has been determined by isotope dilution, and cadmium and telluri um by instrumental neutron activation analysis and inductively coupled plasma mass spectrometry in the dissolved samples. All the samples ha ve also been analysed by secondary ion mass spectrometry. It was shown that P penetrates the film, The first 40 nm contains P in a P/Cd atom ic ratio of about 0.5. In the next layers the ratio is about 0.1. The etchant leaves a thin Te-enriched layer on the surface of the film. Th is was detected from the SIMS profile, but not from the diluted nitric acid dissolved fractions because of the low Te solubility.