Metal-oxide-semiconductor capacitors with erbium oxide dielectrics on In0.53 Ga0.47 As channels

Erbium oxide dielectrics with a thickness of ∼6 nm were fabricated in situ on In0.53 Ga0.47 As channels. Leakage current and capacitance densities were characterized as a function of applied voltage using metal-oxide- semiconductor capacitors with two different top electrode materials, Pt and Al. Leakage current densities were less than 10-3 A/ cm2 at gate voltages up to ±2 V. The capacitance densities were lower with the Al electrode, which was attributed to a low-permittivity aluminum oxide layer at the electrode interface. The capacitors with the Pt electrode showed a pronounced increase in the capacitance in the depletion region at frequencies as high as 1 MHz, which was not observed for the Al electrode. Possible origins of the differences in the capacitance-voltage characteristics with Pt and Al electrodes are discussed.