In situ spectroscopic ellipsometry for real-time monitoring of mercury cadmium telluride/cadmium telluride/silicon growth by MBE.

摘要

Two technologically significant II-VI-semiconductor, heteroepitaxial systems were investigated primarily through crystal growth by molecular beam epitaxy (MBE), and subsequent material characterization. These systems, CdTe/Si and {dollar}rm Hgsb{lcub}1-x{rcub}Cdsb{lcub}x{rcub}Te/Cdsb{lcub}y{rcub}Znsb{lcub}1-y{rcub}Te,{dollar} have important applications for advanced infrared detection systems. The first system, CdTe grown by MBE on Si substrates, was studied on two crystallographic orientations, namely, CdTe (111)B on misoriented Si (001) substrates and CdTe (211)B on Si (211) using a thin ZnTe buffer layer. Layers were characterized by x-ray diffraction, transmission electron microscopy, photoreflectance, and etch pit densities. The growth of {dollar}rm Hgsb{lcub}1-x{rcub}Cdsb{lcub}x{rcub}Te{dollar} by molecular beam epitaxy on bulk {dollar}rm Cdsb{lcub}y{rcub}Znsb{lcub}1-y{rcub}Te{dollar} was monitored using in situ spectroscopic ellipsometry to gather material characteristics of the growing film in real time. The ellipsometer proved to be extremely sensitive to small changes in composition and was capable of measuring the thickness of optically thin films.