“…These include molecular beam epitaxy ͑MBE͒ deposition of Ga 2 O 3 ͑Refs. 1-4͒, in situ [5][6][7] and ex situ 8,9 deposition of amorphous Si ͑a-Si͒ or Ge interlayers, 10,11 atomic hydrogen cleaning of the surface, 12,13 and deposition of different dielectrics in direct contact with the substrate. 14-18 However, the fabrication of III-V based devices is still challenging and significant effort is required to get the best performance.…”