Properties of insulator interfaces with ρ-HgCdTe

Heat treatment at 70 °C of low carrier concentration p-type HgCdTe samples (p₀= 8x 10 cm^-3) generates an inverted surface layer. A two day anneal process below 95 °C did not affect the Hall coefficient, whereas an almost complete recovery was obtained by annealing at 120 °C. While bulk electron mobility, obtained from PEM data, remained high (about 9 X 10 cm/Vs at 77 K), surface mobility is lower by more than an order of magnitude. Surface recombination velocity indicates a continuous improvement with increased temperature, and the activation energy remains equal to the vacancies energy level. The proposed mechanism is that of positive charges in the sulfide migrating towards the interface and generating an image inversion layer.