Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films, volume 43, issue 3

Perspective on comparative radiation hardness of Ga2O3 polymorphs

Stephen J. Pearton ¹

F. Ren ²

A. V. Polyakov ³

K. D. Shcherbachev ^{3, 4}

Leonid Chernyak ⁵

Aman Haque ⁶

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Department of Materials Science and Engineering, University of Florida 1 , Gainesville, Florida 32611 |

Department of Chemical Engineering, University of Florida 2 , Gainesville, Florida 32611 |

Department of Semiconductor Electronics and Semiconductor Physics, National University of Science and Technology MISIS 3 , Leninsky pr. 4, Moscow 119049,

⁴

Institute of Microelectronics Technology and High Purity Materials, Russian Academy of Sciences 4 , Chernogolovka, Moscow Region 142432,

⁵

Department of Physics, University of Central Florida 5 , Orlando, Florida 32816

⁶

Department of Mechanical Engineering, Penn State University 6 , University Park, Pennsylvania 16802

Publication type: Journal Article

Publication date: 2025-03-12

American Vacuum Society

Journal: Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films

scimago Q2

SJR: 0.569

CiteScore: 5.1

Impact factor: 2.4

ISSN: 07342101, 15208559

DOI: 10.1116/6.0004444

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Abstract

Gallium oxide (Ga2O3) exists in different polymorphic forms, including the trigonal (α), monoclinic (β), cubic (γ), and orthorhombic (κ) phases, each exhibiting distinct structural and electronic properties. Among these, β-Ga2O3 is the most thermodynamically stable and widely studied for high-power electronics applications due to its ability to be grown as high-quality bulk crystals. However, metastable phases such as α-, γ-, and κ-Ga2O3 offer unique properties, including wider bandgap or strong polarization and ferroelectric characteristics, making them attractive for specialized applications. This paper summarizes the radiation hardness of these polymorphs by analyzing the reported changes in minority carrier diffusion length (LD) and carrier removal rates under various irradiation conditions, including protons, neutrons, alpha particles, and gamma rays. β-Ga2O3 demonstrates high radiation tolerance with LD reductions correlated to the introduction of electron traps (E2*, E3, and E4) and gallium–oxygen vacancy complexes (VGa–VO). α-Ga2O3 exhibits slightly better radiation hardness similar to κ-Ga2O3, which also shows minimal LD changes postirradiation, likely due to suppressed defect migration. γ-Ga2O3 is the least thermodynamically stable, but surprisingly is not susceptible to radiation-induced damage, and is stabilized under Ga-deficient conditions. The study highlights the role of polymorph-specific defect dynamics, doping concentrations, and nonuniform electrical properties in determining radiation hardness. We also discuss the effect of radiation exposure on the use of NiO/Ga2O3 heterojunction rectifiers that provide superior electrical performance relative to Schottky rectifiers. The presence of NiO does change some aspects of the response to radiation. Alloying with Al2O3 further modulates the bandgap of Ga2O3 and defect behavior, offering potentially tunable radiation tolerance. These findings provide critical insights into the radiation response of Ga2O3 polymorphs, with implications for their use in aerospace and radiation-hardened power electronics. Future research should focus on direct comparisons of polymorphs under identical irradiation conditions, defect identification, and annealing strategies to enhance radiation tolerance.