AVS 66th International Symposium & Exhibition
    Thin Films Division Wednesday Sessions
       Session TF+EM-WeA

Invited Paper TF+EM-WeA3
Development of the β-(AlxGa1-x)2O3/β-Ga2O3 (010) Heterostructures by Plasma-assisted Molecular Beam Epitaxy

Wednesday, October 23, 2019, 3:00 pm, Room A122-123

Session: Emerging Thin Film Materials: Ultra-wide Bandgap and Phase Change Materials
Presenter: James Speck, University of California at Santa Barbara
Correspondent: Click to Email
β-Ga2O3 is a promising wide bandgap semiconductor for power electronics due to its ~4.8 eV bandgap, reasonable electron mobility, the availability of large area melt grown substrates, and the ability to form heterostructures by alloying on the group III site. In this presentation, we present progress in the plasma-assisted molecular beam epitaxy (PAMBE) growth of β-Ga2O3. The presentation will highlight the promise of β-(AlxGa1-x)2O3/β-Ga2O3 heterostructures for lateral devices. We will discuss the growth of β-(AlxGa1-x)2O3 in the context of the predicted high Al solubility in the β-phase (predicted to be up to ~60-70% for growth temperatures > 800 C). Current experiments limit the Al content to ~25% for coherent growth. We will present detailed analysis of the β-(AlxGa1-x)2O3 alloys that show the compositions agree between atom probe tomography and high resolution x-ray diffraction. We will highlight a new growth technique, metal oxide catalyzed epitaxy (MOCATAXY), that enables higher growth temperatures due to the addition of an indium catalyst layer that serves both to react with molecular oxygen in the flux and to suppress Ga2O3 decomposition via the reaction Ga2O3 -> Ga2O+1/2O2. We will demonstrate an increase of growth temperature of ~250 C in comparison to conventional PAMBE growth conditions. We discuss the relative merits and challenges for donor doping in MBE (Si vs. Ge vs. Sn) and options for realizing controllable semi-insulating GaN.