Cu2Te synthesis and in-vacuum thermal decomposition: Chemical-kinetics analysis and comparison to equilibrium vapor-pressure measurements

In this study, polycrystalline Cu-foil substrates are exposed to elemental Te vapor at substrate temperatures below 373 K. Auger electron spectroscopy measurements indicate that copper-telluride films are formed at the substrate surface that have a 2:1 Cu-to-Te ratio, as predicted by the Cu–Te phase diagram. When these films are annealed above about 700 K in vacuum, Te desorbs from the substrate with zero-order kinetics. An analysis of Te-desorption traces that assumes the reaction Cu2Te(s) → 2Cu(s) + αTe(ν) + 1/2(1 − α)Te2(ν) finds a thermal-decomposition activation energy of 217 ± 3 kJ mol− 1. These Te-desorption data are compared to the Te impingement rate calculated from Cu2Te equilibrium vapor-pressure data from the literature and found to be in excellent agreement.