Effects of Cd compensation on the photoluminescence of Cd1-xZnxTe single crystals grown by the modified Bridgman method

In order to deal with the phenomenon of Cd evaporation during the growth of Cd1-xZnxTe (x=0.1) crystals, Cd compensation was adopted during the growth by adding excess Cd into the raw materials. Photoluminescence (PL) spectra were used to investigate the effects of Cd compensation on the properties of Cd1-xZnxTe. A free exciton (FE) peak appeared in the near band-edge region after Cd compensation, which indicated that the concentration of Cd vacancies (VCd) was reduced in Cd1-xZnxTe crystals by Cd compensation. The donor–acceptor pair (DAP) peak became dominant in the PL spectrum and its first and second order phonon replica could also be easily identified after Cd compensation, which was only a weak hump in the case of Cd1-xZnxTe crystals without Cd compensation. It possibly meant that impurities of Al and In were released from the VCd-related complexes. In addition, the deep energy level transition D peak, decreased obviously after Cd compensation, which confirmed that Cd compensation could reduce the dislocation density effectively.