Material synthesis and infrared optical properties of transition metal doped binary and ternary Ⅱ-Ⅵ semiconductors

摘要

We report on the material preparation and optical characterization of transition metal (Cr, Co) doped ternary cadmium chalcogenides for possible applications in mid-infrared (MIR) light source development. Cr~(2+) doped Ⅱ-Ⅵ's (e.g. ZnSe, ZnS) have received significant attention for MIR solid-state laser development in the 2-3 μm region. Transition metal (TM) doped Ⅱ-Ⅵ thin films are also currently being studied for the development of broadly tunable MIR sources pumped through electrical carrier-injection. In this paper, we present results of the material synthesis and IR spectroscopy of several Cr and Co doped cadmium chalcogenides including CdTe, CdMnTe, CdZnTe, CdMgTe, CdCaTe, and CdSrTe. Following the synthesis and purification of undoped Ⅱ-Ⅵ materials, TM doping was achieved during in-situ Bridgman growth or through a thermal diffusion process. The Cr~(2+) doped Ⅱ-Ⅵ materials were characterized by broad IR absorption bands centered at ～1800-1900 ran and MIR emission extending from ～2000-3500 nm. The emission lifetimes varied between 1-5 μs, depending on the Cr concentration and host composition. Co~(2+) doped cadmium chalcogenides exhibited several absorption bands in the infrared region and broad emission extending from ～3-5 μm. Compared to Cr~(2+) doped Ⅱ-Ⅵ's, the emission from Co~(2+) doped cadmium chalcogenides was significantly quenched at room-temperature due to the onset of non-radiative relaxations.