In situ spectroscopic ellipsometry for temperature control in molecular beam epitaxy of HgCdTe

In situ temperature control is required to obtain HgCdTe layers of high crystalline perfection by molecular beam epitaxy. To solve this problem, we used spectroscopic ellipsometry. Various methods have been developed for measuring the temperature before the start of epitaxy. They are based on the analysis of different regions of the ellipsometric spectra of the CdTe buffer layer. An experimental comparison of the suggested methods shows that the temperature measurement accuracy is several degrees, and the sensitivity reaches fractions of a degree. At the stage of stationary growth of layers, it is possible to determine the change in temperature and composition from the kinetics of ellipsometric spectra. Ellipsometric measurements made during the growth of HgCdTe with a sharp change in the heating regime showed correlated changes in both temperature and composition.

Automated summary

In situ temperature control is crucial for obtaining highly crystalline HgCdTe layers by molecular beam epitaxy. Spectroscopic ellipsometry is used to measure the temperature by analyzing different regions of the ellipsometric spectra of the CdTe buffer layer. The temperature measurement accuracy is several degrees with a sensitivity reaching fractions of a degree. Changes in temperature and composition during growth can be determined by studying the kinetics of ellipsometric spectra.