【Member Papers】Investigation of the Degradation Mechanism of β-Ga₂O₃ SBD on 5 MeV Proton Irradiation

      Researchers from the Fudan University have published a dissertation titled "Investigation of the Degradation Mechanism of β-Ga₂O₃ SBD on 5 MeV Proton Irradiation" in IEEE Transactions on Electron Devices.

Project Support

      This work was supported in part by the National Natural Sci ence Foundation of China under Grant U24A20298 and in part by the State Key Laboratory of Radio Frequency Heterogeneous Integra tion under Grant KF2024019.

Background

      Gallium oxide (Ga₂O₃), with its ultrawide bandgap of 4.5–5.1 eV, high breakdown field strength, and high electron saturation rate, has emerged as a focal point in the field of semiconductor materials, particularly for solar-blind deep ultraviolet detection owing to its bandgap aligning with the solar-blind wavelength range. These properties also make Ga₂O₃ an ideal candidate for high-voltage device applications. In recent years, research has focused on the growth and stabilization of different phases of Ga₂O₃ (α, β, γ, δ, and ε) for the realization of high-performance power devices. The large-area growth of single-crystal Ga₂O₃ has been a key breakthrough, driving the progress of Ga₂O₃ technology. Additionally, the high displacement energy of gallium and oxygen atoms in β-Ga₂O₃ provides the material with considerable radiation tolerance, making it suitable for use in harsh space environments where exposure to complex radiation factors is common.

Abstract

      The effects of 5 MeV proton irradiation on the electrical performance of β-Ga₂O₃ Schottky barrier diodes (SBDs) are studied in this article to demonstrate the degradation mechanism and behavior related to defects and energy band. After proton irradiation with a fluence of 10¹³ n/cm², the forward current density of β-Ga₂O₃ SBD decreases, the barrier height rises by 0.2 eV, and the ideality factor degenerates from 1.056 to 1.092. The carrier concentration in the epilayer (from 1.05×10¹⁶ to 0.3×10¹⁶ cm^-3 ), obtained from C–V characteristics, notably reduces due to trap states in the drift layer, leading to a higher barrier height. On the other hand, the Poole-Frenkel emission (PFE) mechanism is found to cause the reverse leakage ofβ-Ga₂O₃ SBD after proton irradiation, utilizing temperature-dependent current-voltage I–V measurements. The deep-level transient spectroscopy (DLTS) measurements further reveal that E_c -0.82 eV (shifted to E_c -0.81 eV) originates from preexisting defects, while E_c -0.72 eV and E_c -1.04 eV are newly introduced by the proton irradiation. The relatively shallow trap states E_c -0.72 eV with a large capture cross section ( 2.25×10^-12 cm^-2 ) contribute to PFE and dominate the trap-assisted leakage. Finally, the lower trap activation energy (from 0.82 to 0.72 eV) and higher Schottky barrier height (from 0.90 to 1.18 eV) both result in the degradation of both forward conduction and reverse leakage in β-Ga₂O₃ SBDs.