SPECTROSCOPIC ELLIPSOMETRY FOR MONITORING AND CONTROL OF MOLECULAR-BEAM EPITAXIALLY GROWN HGCDTE HETEROSTRUCTURES

A systematic study of the effect of measurement perturbation on in sit u monitoring of the composition of molecular beam-epitaxially (MBE) gr own Hg1-xCdxTe using spectroscopic ellipsometry was carried out. Of th e five variables investigated, which included angle of incidence, wave length of the light beam, modulator rotation, analyzer rotation, and m odulator amplitude, the angle of incidence and the modulator rotation had the strongest effect on the in situ Hg1-xCdxTe composition monitor ing process, A wobble-free sample manipulator was installed to reduce the impact of these two variables. With these improvements, the spectr oscopic ellipsometer is now routinely used to monitor Hg1-xCdxTe compo sitions during MBE growth of heterostructures heterostructures and is a useful tool in diagnosing growth-related problems, Examples are incl uded for both application areas, that include the control of the inter face between Hg1-xCdxTe layers of different compositions, i.e. device engineering.