Study of the crystalline quality of CdTe, CdZnTe and CdMnTe substrates used for liquid phase epitaxy of Cd 0.7Hg 0.3Te

Abstract

The crystalline quality of epitaxial layers made of Cd 0.7Hg 0.3Te, which is a very good infrared detector at the optimal transmission wavelength (1.3 μm) in optical fibers, is strongly dependent on the crystalline quality of the substrate. Experimental observations, carried out by means of Berg-Barrett topography, cathodoluminescence, etch-pitting, and X-ray double-crystal rocking curve measurements on several CdTe, Cd 0.96Zn 0.04Te, and Cd 0.9Mn 0.1Te substrates confirm that the addition of Zn results in an improvement of the crystalline quality of the CdTe compound. The best results, in this work, were obtained on Cd 0.96Zn 0.04Te material with an etch-pit density of 5×10 4 cm -2 and an X-ray rocking curve linewidth of 25 arc sec. Mn addition, on the other hand, does not show any change in CdTe crystalline quality. Characterization of Cd 0.7Hg 0.3Te layers grown by liquid phase epitaxy (LPE) on two types of substrates (CdTe, Cd 0.96Zn 0.04Te) has demonstrated the better quality of those epitaxial layers grown on the Cd 0.96Zn 0.04Te substrate. This result constitutes an other indication of the improved crystalline quality of the Cd-rich CdZnTe material.