In Situ Dielectric Al2O3/β‐Ga2O3 Interfaces Grown Using Metal–Organic Chemical Vapor Deposition

Abstract High quality dielectric‐semiconductor interfaces are critical for reliable high‐performance transistors. This paper reports the in situ metal–organic chemical vapor deposition of Al 2 O 3 on β‐Ga 2 O 3 as a potentially better alternative to the most commonly used atomic layer deposition (ALD). The growth of Al 2 O 3 is performed in the same reactor as Ga 2 O 3 using trimethylaluminum and O 2 as precursors without breaking the vacuum at a growth temperature of 600 °C. The fast and slow near interface traps at the Al 2 O 3 /β‐Ga 2 O 3 interface are identified and quantified using stressed capacitance–voltage (CV) measurements on metal oxide semiconductor capacitor (MOSCAP) structures. The density of shallow and deep level initially filled traps (D it ) are measured using ultraviolet‐assisted CV technique. The average D it for the MOSCAP is determined to be 6.4 × 10 11 cm −2 eV −1 . The conduction band offset of the Al 2 O 3 / Ga 2 O 3 interface is also determined from CV measurements and found out to be 1.7 eV which is in close agreement with the existing literature reports of ALD Al 2 O 3 /Ga 2 O 3 interface. The current–voltage characteristics are also analyzed and the average breakdown field is extracted to be approximately 5.8 MV cm −1 . This in situ Al 2 O 3 dielectric on β‐Ga 2 O 3 with improved dielectric properties can enable Ga 2 O 3 ‐based high‐performance devices.