Conductivity of Ga2O3–GaAs Heterojunctions

The effect of annealing in argon at temperatures of Tan = 700–900°C on the I–V characteristics of metal–Ga2O3–GaAs structures is investigated. Samples are prepared by the thermal deposition of Ga2O3 powder onto GaAs wafers with a donor concentration of Nd = 2 × 1016 cm–3. To measure theI–V characteristics, V/Ni metal electrodes are deposited: the upper electrode (gate) is formed on the Ga2O3 film through masks with an area of Sk = 1.04 × 10–2 cm2 and the lower electrode in the form of a continuous metallic film is deposited onto GaAs. After annealing in argon at Tan ≥ 700°C, the Ga2O3-n-GaAs structures acquire the properties of isotype n-heterojunctions. It is demonstrated that the conductivity of the structures at positive gate potentials is determined by the thermionic emission from GaAs to Ga2O3. Under negative biases, current growth with an increase in the voltage and temperature is caused by field-assisted thermal emission in gallium arsenide. In the range of high electric fields, electron phonon-assisted tunneling through the top of the potential barrier is dominant. High-temperature annealing does not change the electron density in the oxide film, but affects the energy density of surface states at the GaAs–Ga2O3 interface.