Ellipsometric thermometry in molecular beam epitaxy of mercury cadmium telluride

Abstract Low temperature in situ control in the technology of HgCdTe layers growing by MBE is a key requirement for obtaining structures of high quality. Spectroscopic ellipsometry seems to be one of the suitable technique for solving this problem. The present paper proposes ellipsometric methods for determining the temperature in the process of pre-epitaxial heat treatment of the samples. The proposed methods are based on the temperature dependence of the optical constants spectra of the CdTe buffer layer. The first method uses the temperature shift of the absorption edge, which is determined from the onset of interference oscillations. It turned out to be resistant to experimental errors and its accuracy proved to be 3–5 °C. The second method is based on comparing the measured and reference spectra. It is much more sensitive to the temperature, but depends strongly on the accuracy of ellipsometric measurements. The combined use of both methods ensures a temperature sensitivity of the order of 1 °C and an accuracy of 3–5 °C.