【International Papers】Trap states and hydrogenation of implanted Si in semi-insulating Ga₂O₃(Fe)

      Researchers from the National University of Science and Technology MISiS have published a dissertation titled " Trap states and hydrogenation of implanted Si in semi-insulating Ga₂O₃(Fe)" in Journal of Vacuum Science & Technology A.

Project Support

      The work at NUST MISIS was supported in part by a grant from the Ministry of Science and Higher Education of Russian Federation (Agreement No. 075-15-2022-1113). The work at UF was performed as part of Interaction of Ionizing Radiation with Matter University Research Alliance (IIRM-URA), sponsored by the Department of the Defense, Defense Threat Reduction Agency, under Award No. HDTRA1-20-2-0002.

Background

      β-Ga₂O₃, with its ultra-wide bandgap (~4.8 eV) and high breakdown field (8–10 MV/cm), is a promising material for next-generation high-power electronics and UV photodetectors. One key challenge in device fabrication is controlled doping, which is crucial for tailoring electrical properties. Si ion implantation is commonly used to introduce n-type doping into β-Ga₂O₃, but the process often leads to unintended defect formation and carrier compensation, reducing activation efficiency.

      Additionally, hydrogen passivation is known to affect defect states and doping behavior in semiconductors. While hydrogenation has been shown to improve electrical performance in some materials, its effects on Si-implanted β-Ga₂O₃ remain poorly understood. This study investigates the electrical properties, deep trap states, and hydrogenation effects in Si-implanted semi-insulating Fe-doped β-Ga₂O₃.

Abstract

      The electrical properties and deep trap spectra of semi-insulating Ga₂O₃(Fe) implanted with Si ions and subsequently annealed at 1000 °C were investigated. A significant discrepancy was observed between the measured shallow donor concentration profile and the profile predicted by Stopping Power and Range of Ions in Matter simulations, indicating substantial compensation. Deep level transient spectroscopy revealed the presence of deep acceptors at E_c −0.5 eV with a concentration of ∼10¹⁷ cm⁻³, insufficient to fully account for the observed compensation. Photocapacitance spectroscopy identified additional deep acceptors with optical ionization thresholds near 2 and 2.8–3.1 eV, tentatively attributed to gallium vacancy-related defects. However, the combined concentration of these deep acceptors still fell short of explaining the observed donor deactivation, suggesting the formation of electrically neutral Si-vacancy complexes. Furthermore, the properties of Ga₂O₃ (Fe) implanted with Si and subjected to hydrogen plasma treatment at 330 °C were also examined. This material exhibited high resistivity with the Fermi level pinned near E_c –0.3 eV, similar to common radiation defects in proton-implanted Ga₂O₃. A prominent deep center near E_c −0.6 eV, consistent with the known E1 electron trap attributed to Si-H complexes, was also observed. These results highlight the challenges associated with Si implantation and activation in Ga₂O₃ and suggest that hydrogen plasma treatment, while effective for Ga-implanted Ga₂O₃ is less suitable for Si-implanted material due to the formation of compensating Si-H complexes.