AN EVALUATION OF THE SESSILE DROP TECHNIQUE FOR THE STUDY OF (HG, CD)TE SURFACES

The sessile drop technique is a method of evaluating and comparing surfaces by measuring the contact angle between a liquid drop and the surface on which it is placed. The technique is extremely sensitive to the outermost surface layer and is thus a potentially useful tool for the evaluation, comparison and monitoring of (Hg, Cd)Te surfaces subjected to various chemical treatments. In this study, drops of deionized water were used to show that many chemicals commonly used in (Hg, Cd)Te processing create surfaces with characteristic contact angles: e.g. ozone < 10-degrees, concentrated hydrogen peroxide 45-degrees, 0.5 vol% Br/methanol solution 73-degrees. Sulphuric and nitric acids gave values that were dependent on chemical concentration The kinetics of oxidation of a chemically treated (Hg, Cd)Te surface were monitored by x-ray photoelectron spectroscopy and the sessile drop technique, with good agreement. Ellipsometry and the sessile drop method were in good agreement during the monitoring of the initial stages of surface film growth.