Electrical Characteristics of ${\rm Al}_{2}{\rm O}_{3}/{\rm InSb}$ MOSCAPs and the Effect of Postdeposition Annealing Temperatures

The characteristics of ${\rm Al}_{2}{\rm O}_{3}/{\rm InSb}$ MOSCAPs processed with different postdeposition annealing (PDA) temperatures are investigated. X-ray photoelectron spectroscopy analysis shows a significant reduction of InSb-oxides after HCl plus trimethyl aluminum treatment and oxide deposition. Multifrequency capacitance-voltage $(C\hbox {--}V)$ characteristics exhibit low-frequency and asymmetrical $C\hbox {--}V$ behaviors, in which capacitance in the InSb conduction band side is lower than in the valence band side. The electrical properties of the MOSCAPs are sensitive to PDA temperature and degraded significantly at PDA temperature ${>}{\rm 300}^{\circ}{\rm C}$ . This degradation is closely related to the diffusion of In, Sb into ${\rm Al}_{2}{\rm O}_{3}$ as indicated by transmission electron microscopy analyses.