Quasistatic and high frequency capacitance–voltage characterization of Ga2O3–GaAs structures fabricated by in situ molecular beam epitaxy

Interface properties of Ga2O3–GaAs structures fabricated using in situ multiple-chamber molecular beam epitaxy have been investigated. The oxide films were deposited on clean, atomically ordered (100) GaAs surfaces at ≂600 °C by electron-beam evaporation using a Gd3Ga5O12 single-crystal source. Metal–insulator–semiconductor structures have been fabricated in order to characterize the Ga2O3–GaAs interface by capacitance–voltage measurements in quasistatic mode and at frequencies between 100 Hz and 1 MHz. The formation of inversion layers in both n and p-type GaAs has been clearly established. Using the quasistatic/high frequency technique, the interface state density has been derived as a function of band gap energy and a midgap interface state density in the mid 1010 cm−2 eV−1 range has been inferred. Charge trapping in the oxide has been revealed as the dominant trapping mechanism.