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

Abstract The growth and bonding chemistry at a gate dielectric Ga 2 O 3 /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 Ga 2 O 3 on a (2×4) reconstructed GaAs surface proceeds with molecules of Ga 2 O insertion into pairs of As-dimers with the surface void of As–O bonding. Subsequent growth involved the combination of Ga 2 O with oxygen to form Ga 2 O 3 . However, for stoichiometric Ga 2 O 3 , 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.