Evidence of electron and hole inversion in GaAs metal-oxide-semiconductor capacitors with HfO2 gate dielectrics and α-Si/SiO2 interlayers

Evidence of inversion in GaAs metal-oxide-semiconductor capacitors with HfO2 gate dielectrics and alpha-Si/SiO2 interlayers is reported. Capacitors formed on n-GaAs with atomic layer-deposited HfO2 displayed C-V characteristics with minimum D-it of 7x10(11) cm(-2)/eV, while capacitors with molecular beam epitaxy-deposited HfO2 on p-GaAs had D-it=3x10(12) cm(-2)/eV. Lateral charge transport was confirmed using illuminated C-V measurements on capacitors fabricated with thick Al electrodes. Under these conditions, capacitors on n-GaAs (p-GaAs) showed "low-frequency" C-V behavior, indicated by a sharp capacitance increase and saturation at negative (positive) gate bias, confirming the presence of mobile charge at the semiconductor/dielectric interface.