Mechanisms of laser-induced defect formation and In doping in CdTe crystals

Abstract

The laser-stimulated modification of the crystalline and point defect structure of the surface layer of CdTe crystals was studied and laser-induced doping was performed to form electrical barriers in the surface region of samples. The results of comprehensive investigations of time-resolved optical reflectivity, atomic force microscopy, reflection of high-energy electron diffraction, current-voltage characteristics, exciton photoluminescence in (111)B oriented CdTe crystals subjected to irradiation with nanosecond KrF excimer laser pulses have been discussed. The peculiarities of pulsed-laser-induced melting and following crystallization of the CdTe surface depending on laser energy density have been analyzed. The melting and ablation thresholds were determined as 50 mJ/cm/sup 2/ and 145 mJ/cm/sup 2/, respectively. Using laser irradiation of CdTe crystals pre-coated with an indium dopant film, it was possible to suppress the self-compensation mechanism and fabricate the CdTe-based diodes promising for nuclear radiation detectors. The mechanisms of laser-induced defect formation and doping have been discussed.