Influence of laser irradiation and laser-induced In doping on the photoluminescence of CdTe crystals

By investigating the photoluminescence (PL), we have studied laser-induced doping and defect formation in high-resistivity Cl-compensated p-like CdTe crystals coated with and without a thin In dopant film. A detailed analysis of the PL spectra has been performed to discuss the laser-stimulated modification of the defect structure in CdTe crystals subjected to irradiation with nanosecond KrF excimer laser pulses with the energy density above the melting threshold. In particular, laser irradiation increased V-Cd as a result of the dissociation of (Cd-X) complexes and laser desorption of Cd atoms. Laser-stimulated diffusion of In atoms at Cd vacancies provided doping of CdTe crystals. Fast freezing of a large number of the point defects In-Cd impeded the formation of compensating acceptors (V-Cd-In-Cd). This allows us to suppress the self-compensation mechanism, and to introduce and activate the In impurity into a thin surface layer of the crystals without damaging of the structure and properties of the underlying region.