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 sur faces by measuring the contact angle between a liquid drop and the sur face on which it is placed. The technique is extremely sensitive to th e outermost surface layer and is thus a potentially useful tool for th e evaluation, comparison and monitoring of (Hg, Cd)Te surfaces subject ed to various chemical treatments. In this study, drops of deionized w ater were used to show that many chemicals commonly used in (Hg, Cd)Te processing create surfaces with characteristic contact angles: e.g. o zone < 10-degrees, concentrated hydrogen peroxide 45-degrees, 0.5 vol% Br/methanol solution 73-degrees. Sulphuric and nitric acids gave valu es that were dependent on chemical concentration The kinetics of oxida tion of a chemically treated (Hg, Cd)Te surface were monitored by x-ra y photoelectron spectroscopy and the sessile drop technique, with good agreement. Ellipsometry and the sessile drop method were in good agre ement during the monitoring of the initial stages of surface film grow th.