Annealing behavior of undoped Hg0.8Cd0.2Te epitaxial films at low temperatures

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Abstract
Hall‐effect measurements were carried out on undoped Hg0.8Cd0.2Te films which were grown liquid‐phase epitaxially from Te‐rich solutions and were annealed under different partial pressures of Hg at temperatures varying from 150 to 500 °C. Within the phase boundary limits of the material, the hole concentration in the films was found to increase with decrease in the partial pressure of Hg in agreement with the previously reported behavior of undoped bulk Hg0.8Cd0.2Te crystals at temperatures in the range of 400–655 °C. The hole concentration was found to be independent of the partial pressure of Hg at extremely low Hg pressures and is interpreted to be the consequence of the crystals reaching the phase boundary limits. Limits of partial pressure of Hg under Te‐saturated conditions at temperatures below 500 °C have been deduced from the electrical data. Previously published values of the equilibrium constants Ki and K‘VHg for the intrinsic excitation reaction and for the incorporation of the doubly ionized native acceptor defect deduced for the bulk crystals at temperatures in excess of 400 °C, also satisfactorily explain the electrical data on the epitaxial films at temperatures below 400 °C.