摘要
In-situ molecular beam epitaxy (MBE) Y 2 O 3 films 1-2nm thick were epitaxially grown on GaAs(001)-4×6 reconstructed surfaces. Despite a large lattice mismatch, the hetero-structure exhibits outstanding thermal stability to 900°C with excellent capacitance-voltage (C-V) characteristics. Low interfacial trap densities (D it 's) of (3-5)×10 11 eV -1 cm -2 were obtained using the conductance method (G-V) without discernible peaks at the mid-gap. The frequency dispersion of the measured C-Vs of the Y 2 O 3 /GaAs(001) is ~4.6% for p-GaAs and ~12.4% for n-GaAs. In contrast, the atomic layer deposited Al 2 O 3 on GaAs(001) shows large D it with a peak at the mid-gap, large C-V frequency dispersion, and low thermal stability at temperatures higher than 600°C. Synchrotron radiation photoemission results show intactness of the interfacial structure in the MBE-Y 2 O 3 /GaAs, while removal of the surface As atoms is found in the ALD-Al 2 O 3 /GaAs system.