Progress and challenges in the development of ultra-wide bandgap semiconductor α-Ga2O3 toward realizing power device applications

Abstract

Ultra-wide-bandgap (UWBG) semiconductors, such as Ga2O3 and diamond, have been attracting increasing attention owing to their potential to realize high-performance power devices with high breakdown voltage and low on-resistance beyond those of SiC and GaN. Among numerous UWBG semiconductors, this work focuses on the corundum-structured α-Ga2O3, which is a metastable polymorph of Ga2O3. The large bandgap energy of 5.3 eV, a large degree of freedom in band engineering, and availability of isomorphic p-type oxides to form a hetero p–n junction make α-Ga2O3 an attractive candidate for power device applications. Promising preliminary prototype device structures have been demonstrated without advanced edge termination despite the high dislocation density in the epilayers owing to the absence of native substrates and lattice-matched foreign substrates. In this Perspective, we present an overview of the research and development of α-Ga2O3 for power device applications and discuss future research directions.

Carrier removal rates in 1.1 MeV proton irradiated α-Ga2O3 (Sn)

“…The ultra-wide bandgap semiconductor Ga 2 O 3 is attracting interest because of the potential for application in highpower electronic devices and in deep UV efficient solarblind photodetectors [1][2][3][4][5][6]. The main thrust of the work has concentrated on the thermodynamically stable monoclinic β-Ga 2 O 3 polymorph with its high electric breakdown field of ∼8 MV cm −1 , exceeding by several times those of GaN and SiC.…”

“…There is also interest in the metastable corundum α-Ga 2 O 3 polymorph [1,2,[4][5][6]. This has a higher bandgap of 5.1 eV versus 4.8 eV for β-Ga 2 O 3 , higher symmetry (corundum versus monoclinic), the existence of corundum structure metal oxides showing p-type conductivity and available for fabrication of useful heterostructure devices, and finally, the possibility to grow on sapphire (α-Al 2 O 3 ) substrates [1,4,5,[7][8][9][10][11][12][13][14][15][16][17][18][19][20].…”

Control of Al composition of mist chemical vapor deposition grown α-(AlGa)2O3 alloy thin films by acetylacetonation of Al ion

“…Gallium oxide is an attractive oxide-semiconductor material [1][2][3][4] due to its wide bandgap energy and high dielectric breakdown field 5) for high-power devices [6][7][8] and DUV optical-device applications. 9) Ga 2 O 3 has at least five different polymorphs, namely, α, β, γ, δ, and κ phases.…”

Mechanism for Long Photocurrent Time Constants in α-Ga2O3 UV Photodetectors

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14] For power devices, the main advantages of Ga 2 O 3 are due to the electric breakdown field exceeding by several times the breakdown field of III-Nitrides or SiC due to the large bandgap of ∼5 eV. [1][2][3][4][5][6][7][8][9][10][11] Additionally, the thermodynamically stable monoclinic β-Ga 2 O 3 polymorph allows economic growth of high-quality substrate material from the melt, applicability of all major epitaxial techniques to growth of device-quality epilayers, while the metastable corundum structure α-Ga 2 O 3 can be epitaxially grown on cheap isomorphic α-Al 2 O 3 sapphire substrates and can be utilized to create heterojunctions with a wide range of corundum structured oxides of Al, In, or transition metals and rare metals. [1][2][3][4][5][6]9,15 For photodetectors, the advantages are the wide bandgap and a low density of deep centers, which makes the material solar-blind, with high photosensitivity.…”

“…[1][2][3][4][5][6][7][8][9][10][11] Additionally, the thermodynamically stable monoclinic β-Ga 2 O 3 polymorph allows economic growth of high-quality substrate material from the melt, applicability of all major epitaxial techniques to growth of device-quality epilayers, while the metastable corundum structure α-Ga 2 O 3 can be epitaxially grown on cheap isomorphic α-Al 2 O 3 sapphire substrates and can be utilized to create heterojunctions with a wide range of corundum structured oxides of Al, In, or transition metals and rare metals. [1][2][3][4][5][6]9,15 For photodetectors, the advantages are the wide bandgap and a low density of deep centers, which makes the material solar-blind, with high photosensitivity. 2,3,7,8,10,13 The external quantum efficiency of Ga 2 O 3 photodetectors demonstrates an unusually high gain, not uncommonly exceeding 10 1 −10 5 .…”