Capacitance-voltage Characterization of Atomic-Layer-Deposited Al2O3/InGaAs and Al2O3/GaAs Metal –Oxide-Semiconductor Structures

ALD Al2O3/GaAs and Al2O3/In0.2Ga0.8As MOS and source-drain implanted MOSFET structure were fabricated and characterized by capacitance-voltage (CV) and current-voltage (I-V) measurements. It is shown that, after high-temperature anneal, the MOS leakage current density of the thinner (16nm) film is much higher than that of the thicker (30nm) film. The highquality Al2O3 (30nm)/In0.2Ga0.8As interface after high temperature anneal is verified by C-V curves showing sharp transition from depletion to accumulation with “zero” hysteresis, 1% frequency dispersion per decade at accumulation capacitance and strong inversion under split C-V measurement. However, Al2O3(16nm)/GaAs shows larger hysteresis and frequency dispersion with no inversion layer formed under split C-V measurement. Photo-assisted C-V measurement shows the inversion layer easily formed on In0.2Ga0.8As interface but not on GaAs interface, indicating higher surface recombination rate at GaAs interface. The estimated interface trap density (Dit) by split C-V method shows 2.9×10/cmeV for Al2O3/In0.2Ga0.8As. Minority-carrier response of Al2O3/In0.2Ga0.8As and Al2O3/GaAs is systematically studied by high-temperature C-V measurements which reveal the activation energy (EA) of the minority-carrier recombination to be about 0.62 ± 0.03 eV for InGaAs and 0.71 ± 0.01 eV for GaAs, respectively.