Local atomic structure of CdTe:In at high In concentrations

The local atomic structure of CdTe:In at In concentrations of 0, 0.5, and 6 at. % was investigated using x-ray absorption spectroscopy. Changes in the x-ray-absorption near-edge structure (XANES) and the x-ray-absorption fine structure (XAFS) were detected for the In K edge. In the In XANES region, the 0.5 at. % sample exhibits a higher amplitude of the white line than the 6 at. % sample. While in the In K-edge XAFS of both samples only the first shell contribution is apparent; the environment around In in the 0.5 at. % sample shows larger disorder than in the 6 at. % In sample. From Cd and Te XAFS the data exhibit the first three shells of neighbors in agreement with the zinc-blende structure of CdTe, showing increased disorder as a function of In concentration. Results from fits and simulations of both XAFS and XANES indicate the formation of A centers in the 0.5 at. % sample. For the 6 at. % sample the results indicate a smaller amount of A centers. The possibility of DX center formation is discussed.