Al Incorporation up to 99% in Metalorganic Chemical Vapor Deposition‐Grown Monoclinic (Al_xGa_1–x)₂O₃ Films Using Trimethylgallium

Abstract

Growths of monoclinic (AlxGa1−x)2O3 thin films up to 99% Al contents are demonstrated via metalorganic chemical vapor deposition (MOCVD) using trimethylgallium (TMGa) as the Ga precursor. The utilization of TMGa, rather than triethylgallium, enables a significant improvement of the growth rates (>2.5 μm h−1) of β‐(AlxGa1−x)2O3 thin films on (010), (100), and (01) β‐Ga2O3 substrates. By systematically tuning the precursor molar flow rates, growth of coherently strained phase pure β‐(AlxGa1−x)2O3 films is demonstrated by comprehensive material characterizations via high‐resolution X‐ray diffraction (XRD) and atomic‐resolution scanning transmission electron microscopy (STEM) imaging. Monoclinic (AlxGa1−x)2O3 films with Al contents up to 99, 29, and 16% are achieved on (100), (010), and (01) β‐Ga2O3 substrates, respectively. Beyond 29% of Al incorporation, the (010) (AlxGa1−x)2O3 films exhibit β‐ to γ‐phase segregation. β‐(AlxGa1−x)2O3 films grown on (01) β‐Ga2O3 show local segregation of Al along (100) plane. Record‐high Al incorporations up to 99% in monoclinic (AlxGa1−x)2O3 grown on (100) Ga2O3 are confirmed from XRD, STEM, electron nanodiffraction, and X‐ray photoelectron spectroscopy measurements. These results indicate great promises of MOCVD development of β‐(AlxGa1−x)2O3 films and heterostructures with high Al content and growth rates using TMGa for next‐generation high‐power and high‐frequency electronic devices.

Density Functional Theory Study of Polarization-Induced Electron Confinement by Dilute Boron Alloying in ε-Ga2O3 Nanometer-Thick Film for High Electron Mobility Transistor

“…The process of alloying is a prevalent technique utilized to modify the properties of materials, and it is extensively employed within the semiconductor industry. − The growth of alloying on the material itself presents numerous advantages over the combination of different materials. This is exemplified in the AlGaN/GaN HEMT, where the lattice mismatch is relatively small, and the interface quality is adequate for practical applications.…”

Bandgap engineering and Schottky barrier modulation of ultra-wide bandgap Si-doped β-(AlxGa1−x)2O3 single crystals

“…An orbital hybrid appears with the formation of β-AlGaO to change the position of E C , 14 achieving the goal of widening the bandgap and making it more suitable for extreme environmental power electronics applications. At present, the epitaxial growth of β-AlGaO on Ga 2 O 3 has been widely studied, 15–17 Zhang reported ∼2790 cm 2 V −1 s −1 low-temperature mobility in the β-AlGaO/Ga 2 O 3 heterostructure. 18 Okumura et al demonstrated β-AlGaO metal–semiconductor field effect transistors.…”

MOCVD Growth of β-Ga2O3 on (001) Ga2O3 Substrates

“…Due to its promising fundamental material properties, such as a large energy bandgap (4.8 eV), , controllable n-type doping, − and a high predicted breakdown field strength (8 MV/cm), β-Ga 2 O 3 has emerged as a promising semiconductor candidate for the development of next-generation high-power electronic devices . Another key advantage of β-Ga 2 O 3 over other wide (GaN, SiC) and ultrawide (diamond, AlN) bandgap semiconductors is the availability of high-quality, single-crystalline native substrates with various orientations, enabling high-quality epitaxy of β-Ga 2 O 3 − ,− and β-(Al x Ga 1– x ) 2 O 3 alloys. − While the technology is in its nascent stage, significant strides have been made in creating β-Ga 2 O 3 -based devices using bulk and epitaxial thin films, such as lateral and vertical field-effect transistors and Schottky barrier diodes (SBDs) with high breakdown voltages surpassing 6 kV. − …”