Low interfacial density of states around midgap in MBE-Ga2O3(Gd2O3)/In0.2Ga0.8As

Abstract Systematic temperature-dependent capacitance-voltage and conductance measurements were used to study the electrical characteristics of molecular beam epitaxy (MBE) and atomic layer deposition (ALD) oxides on In 0.2 Ga 0.8 As/GaAs. The distribution of interfacial density of states ( D it ) within the band gap of In 0.2 Ga 0.8 As was deduced with the conductance method. The MBE-grown Ga 2 O 3 (Gd 2 O 3 )/In 0.2 Ga 0.8 As, with an excellent tailored interface, has given D it values of ∼5×10 11  eV −1  cm −2 above, ∼2×10 12  eV −1  cm −2 below, and 1–7×10 12  eV −1  cm −2 around the mid-gap region (0.5–0.7 eV above valence band maximum ( E V )); the high D it value near the mid-gap, extracted at 100 and 150 °C, may be related to the temperature effect, which tends to induce more trap excitations. In contrast, the ALD-Al 2 O 3 /In 0.2 Ga 0.8 As has yielded higher D it values of>10 13  eV −1  cm −2 around the mid-gap region.