In-Situ Ellipsometry Studies of Adsorption of Hg on CdTe(211)B/Si(211) and Molecular Beam Epitaxy Growth of HgCdTe(211)B

摘要

We study the adsorption of Hg on CdTe(211)B using an 88-wavelength spec-troscopic ellipsometer mounted on a commercial,molecular beam epitaxy (MBE) chamber.A detailed analysis of the pseudo-dielectric function shows that Hg is present at the surface both in chemisorbed and physisorbed form.Effective medium models for a mixture of chemisorbed and physisorbed Hg on the microscopically rough CdTe surface could not fit our data.However,a proposed model in which a partial layer of physisorbed Hg sits on top of a partial layer of chemisorbed Hg fits the measured pseudo-dielectric function well and yields precise values for the thicknesses of the chemisorbed and the physisorbed Hg layers.These values change in the expected manner as a function of Hg flux,temperature,and Te coverage.An analysis of the uncertainty in the measured thicknesses is carried out in detail,and a study of the limitations of the ellipsometer used for this study is presented.The effects of these limitations on the precision and accuracy of in-situ data are enumerated.