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In this work, transmission electron microscopy has been used to investigate HgCdSe/ZnTe/Si (211) heterostructures grown by molecular beam epitaxy and to study the effects of chemical etchants for measurements of defect density in the HgCdSe epilayers. Both ZnTe/Si and HgCdSe/ZnTe interfaces were decorated with {111}-type stacking faults inclined at angles of ∼ 19° or ∼ 90° with respect to the interface plane. Similar stacking faults were also present in the upper regions of the HgCdSe films. High-resolution imaging and Fourier image analysis revealed dislocations, mostly with a31¯11 Burgers vector, at both ZnTe/Si and HgCdSe/ZnTe interfaces. Etching solutions based on different combinations of nitric acid, hydrochloric acid and lactic acid were tried in attempts to identify an etchant that provided one-to-one correspondence between etch pits and defects in the HgCdSe layer. Focused-ion-beam milling and transmission electron microscopy were used to prepare site-specific cross-section samples from across the etch pits. However, many defects in regions surrounding the etch pits were unaffected by the various different etchants. [ABSTRACT FROM AUTHOR]

We are engaged in a systematic study of the optical and laser properties of Cr2+-doped cadmium chalcogenides. Previously, we demonstrated quasi-continuous wave lasing from Cr2+-doped Cd0.55Mn0.45Te with slope efficiencies as high as 64% and a laser tuning range from 2,170–3,010 nm. In this paper, we report the first demonstration of lasing from Cr:CdTe at room temperature. Pulsed-laser operation was obtained with a free-running spectrum centered at 2,535 nm. The slope efficiency of the laser was low (∼1%) because of large parasitic losses at the laser wavelength. The spectroscopic properties of Cr:CdTe are favorable for laser applications because of a large emission cross section (∼2.5 × 10−18 cm2) and a high emission-quantum yield (∼88%). In addition, CdTe can easily incorporate Cr ions either through melt growth or diffusion doping. Along with our results on Cr2+:CdTe, we report on the optical properties of several other Cr2+-doped II-VI semiconductors (ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, Cd0.9Zn0.1Te, Cd0.65Mg0.35Te, Cd0.85Mn0.15Te, and Cd0.55Mn0.45Te) and compare them for applications as solid-state laser materials. [ABSTRACT FROM AUTHOR]