Growth of Various Phases of Gallium Oxide

Abstract

In this article, we review the growth of various phases of gallium oxides (Ga2O3). There are five polymorphs of Ga2O3, α, β, γ, δ, and ϵ (or κ), of which β‐gallia is the most thermodynamically stable one. In the past decade, remarkable advancements in producing β‐Ga2O3bulk substrates have been made. At present, 4‐inch β‐Ga2O3substrates are commercially available. The other phases of Ga2O3are less thermally stable; however, the material properties of different crystal structures suggest their potential for a broad range of applications. In order to better understand the characteristics of various phases of Ga2O3, growth methods for bulk and epitaxial thin films of Ga2O3and structural properties are reviewed herein.

Controlled Crystallinity of a Sn-Doped α-Ga2O3 Epilayer Using Rapidly Annealed Double Buffer Layers

“…The most thermally stable phase among them (the monoclinic β structure) has been exclusively grown as a single crystal bulk at a melting temperature of ~1800 [ 8 ]. The rhombohedral α-Ga 2 O 3 , while thermodynamically metastable, boasts the widest bandgap (5.3 eV) and a high breakdown voltage relative to other Ga 2 O 3 crystal phases [ 9 , 10 ]. Despite the lattice constant differences of approximately 3.3% and 4.8% in the c - and a -axes, heteroepitaxial α-Ga 2 O 3 thin films have been successfully grown on sapphire (α-Al 2 O 3 ) substrates [ 11 ], leading to the generation of misfit dislocation in a period of 8.6 nm along the [1 00] direction at the interface between the α-Ga 2 O 3 epilayer and the sapphire substrate [ 12 , 13 ].…”

α-Gallium Oxide Films on Microcavity-Embedded Sapphire Substrates Grown by Mist Chemical Vapor Deposition for High-Breakdown Voltage Schottky Diodes

“…In comparison to SiC and GaN, Ga 2 O 3 has a larger band gap energy ranging from 4.8 to 5.3 eV and a huge breakdown field of roughly 8 MV/cm. 5,6 Furthermore, the Baliga figure of merit (BFOM), which indicates a material's potential for high-power and high-voltage applications, is expected to be substantially greater for Ga 2 O 3 than for Si, SiC, or GaN. 6,7 As a result, Ga 2 O 3 is predicted to be used to fabricate power devices with high breakdown voltages and low on-resistances.…”

“…5,6 Furthermore, the Baliga figure of merit (BFOM), which indicates a material's potential for high-power and high-voltage applications, is expected to be substantially greater for Ga 2 O 3 than for Si, SiC, or GaN. 6,7 As a result, Ga 2 O 3 is predicted to be used to fabricate power devices with high breakdown voltages and low on-resistances. Furthermore, Ga 2 O 3 's high breakdown field will be advantageous for fabricating efficient and compact devices with low heat generation since relatively thin drift layers are required.…”

“…Meanwhile, as the commercialization of SiC- and GaN-based devices begins, gallium oxide (Ga 2 O 3 ) is garnering the interest of researchers exploring materials for next-generation power devices with high breakdown voltages and efficiency. In comparison to SiC and GaN, Ga 2 O 3 has a larger band gap energy ranging from 4.8 to 5.3 eV and a huge breakdown field of roughly 8 MV/cm. , Furthermore, the Baliga figure of merit (BFOM), which indicates a material’s potential for high-power and high-voltage applications, is expected to be substantially greater for Ga 2 O 3 than for Si, SiC, or GaN. , As a result, Ga 2 O 3 is predicted to be used to fabricate power devices with high breakdown voltages and low on-resistances. Furthermore, Ga 2 O 3 ’s high breakdown field will be advantageous for fabricating efficient and compact devices with low heat generation since relatively thin drift layers are required.…”

“…For growing α-Ga 2 O 3 films, we used mist CVD, which is an atmospheric growth apparatus noted for its structural simplicity and cheap deposition cost. The CVD has played a key role in the α-Ga 2 O 3 research field, spanning epitaxial growth, ,− alloying, ,,,− doping, − and device fabrications. ,, In this work, we investigated the influence of MESS on the crystallinity and residual stress of α-Ga 2 O 3 films as well as the growth behavior of α-Ga 2 O 3 films on MESS. In addition, we explored the relationship between TD density and breakdown voltages in Schottky diodes (SDs) manufactured with high-quality α-Ga 2 O 3 films on MESS.…”