THERMAL-STABILITY OF SUBSTITUTIONAL AG IN CDTE

The thermal stability of substitutional Ag in CdTe was deduced from la ttice location measurements at different temperatures. Substitutional Ag probe atoms were generated via transmutation doping from radioactiv e Cd isotopes. The lattice sites of Ag isotopes were determined by mea suring the channeling effects of emitted conversion electrons. Below r oom temperature Ag occupies mainly substitutional lattice sites. With increasing measurement temperature the substitutional fraction of Ag a toms decreases and vanishes completely above 400 K. Simultaneously mea sured loss of Ag activity indicates that some of the Ag diffuses prefe rentially to the surface where it disappears. The remaining Ag may be trapped at extended defect complexes or precipitates. In Cd-rich CdTe we suspect an interstitial diffusion directly after the dissociation t o the sinks, whereas in Te-rich CdTe this process is possibly retarded by retrapping at Cd vacancies.