Crystal growth and infrared spectroscopy of Cr:Cd1−xZnxTe and Cr:Cd1−xMgxTe

The absorption and emission properties of Cr2+-doped II-VI semiconductors are of considerable current interest for applications in mid-infrared (MIR) solid-state lasers and for passive optical Q-switches. In this paper, the crystal growth and compositional effects on the optical properties of Cr:Cd1−xZnxTe (x=0.05, 0.1, 0.2) and Cr:Cd1−xMgxTe (x=0.15, 0.35) were investigated. Undoped Cd1−xZnxTe and Cd1−xMgxTe crystals were grown by Bridgman technique. Cr doping of both materials was achieved either in situ during growth or through a thermal diffusion process. For Cr:Cd1−xZnxTe, the Cr2+ absorption properties were strongly dependent on the host composition and spectral blue shifts were observed with increasing Zn content. The Cr2+ absorption peak shifted from ∼1910 nm for Cr:CdTe to ∼1815 nm for Cr:Cd0.8Zn0.2Te. Only small spectral shifts were observed for the MIR emission from Cr:Cd1−xZnxTe. On the contrary, the optical properties of Cr2+ in Cr:Cd1−xMgxTe were nearly independent of the host composition and resembled Cr:CdTe.