In-situ XPS and RHEED study of gallium oxide on GaAs deposition by molecular beam epitaxy

The growth and bonding chemistry at a gate dielectric Ga2O3/GaAs interface is investigated using in-situ photoemission techniques. A multi-chamber molecular beam epitaxy/analysis system allows for the controlled deposition of III-V and oxide layers and the probing of these layers without exposure to atmosphere. The growth of Ga2O3 on a (2×4) reconstructed GaAs surface proceeds with molecules of Ga2O insertion into pairs of As-dimers with the surface void of As-O bonding. Subsequent growth involved the combination of Ga2O with oxygen to form Ga2O3. However, for stoichiometric Ga2O3, the substrate temperature >440 °C is required to provide the necessary energy for the reaction. This growth process is unique and represents a method for unpinning the Fermi level for GaAs with a low level of interface state density required for the fabrication of enhancement mode MOSFET devices.