Capacitance-voltage Characterization of Atomic-Layer-Deposited Al{sub}2O{sub}3/InGaAs and Al{sub}2O{sub}3/GaAs Metal-Oxide-Semiconductor Structures

摘要

ALD Al{sub}2O{sub}3/GaAs and Al{sub}2O{sub}3/In{sub}0.2Ga{sub}0.8As MOS and source-drain implanted MOSFET structure were fabricated and characterized by capacitance-voltage (C-V) 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 high-quality Al{sub}2O{sub}3 (30nm)/In{sub}0.2Ga{sub}0.8As 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, Al{sub}2O{sub}3(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 In{sub}0.2Ga{sub}0.8As interface but not on GaAs interface, indicating higher surface recombination rate at GaAs interface. The estimated interface trap density (D{sub}(it)) by split C-V method shows 2.9×10{sup}11/cm{sup}2-eV for Al{sub}2O{sub}3/In{sub}0.2Ga{sub}0.8As. Minority-carrier response of Al{sub}2O{sub}3/In{sub}0.2Ga{sub}0.8As and Al{sub}2O{sub}3/GaAs is systematically studied by high-temperature C-V measurements which reveal the activation energy (E{sub}A) of the minority-carrier recombination to be about 0.62 ± 0.03 eV for InGaAs and 0.71 ± 0.01 eV for GaAs, respectively.