Ellipsometric Method of Substrate Temperature Measurement in Low-Temperature Processes of Epitaxy of InSb Layers

The present study is aimed at solving the problem of in situ thermometry of lowtemperature processes of molecular beam epitaxy of indium antimonide. A spectral ellipsometric method for measuring the temperature of InSb epitaxial layers is proposed. The method is based on the temperature dependence of the energy positions of the critical points. The spectra of ellipsometric parameters of the material in the temperature range from 25 to 270 °C are measured. The analysis of these spectra shows that the most temperature-sensitive parameters are the spectral positions of the peaks of the ellipsometric parameter, which are manifested near the critical points E ₁ and E ₁ + Δ ₁ . It is found that the dependences of the peak positions on temperature in the above-mentioned temperature range are linear functions with the slope factors of 0.21 and 0.10 nm/°C, respectively. These factors determine the sensitivity of the method and ensure the temperature measurement accuracy within 2–3 °C.