1GeV proton damage in β-Ga2O3

The changes of electrical properties and deep trap spectra induced in n-type beta-Ga2O3 by 1GeV protons with a fluence of 4x10(13)cm(-2) were studied. The carrier removal rates were similar to 100cm(-1) at this energy. For comparison, for 20MeV proton irradiation at comparable fluences (5-10x10(14)cm(-2)), the removal rate was similar to 400cm(-1) for donor concentrations of 3x10(16)cm(-3) and similar to 100cm(-1) for concentrations of <10(16)cm(-3). These removal rates were in stark contrast with modeling results that predicted the introduction rates of vacancies to be two orders of magnitude higher for 20MeV protons. Measurements of deep electron and hole traps densities by deep level transient spectroscopy with electrical or optical injection (DLTS or ODLTS), and capacitance-voltage profiling under monochromatic light illumination showed that the 1GeV proton irradiation resulted in the introduction of deep donors E2*(E-c-0.75eV) and E3 (E-c-1eV) and deep acceptors with optical ionization threshold near 2.3eV producing a feature near 250K in ODLTS and 3.1eV with related ODLTS feature near 450K. The total concentration of all deep traps was much lower than that necessary to explain the observed decrease in net donor density upon irradiation. The donor densities showed a nonuniform distribution in proton irradiated films with the concentration greatly decreased toward the surface. Possible reasons for the observed performance are discussed.

Automated summary

The study found that 1GeV proton irradiation induced the introduction of deep donors E2*(E-c-0.75eV) and E3 (E-c-1eV) as well as deep acceptors with optical ionization threshold near 2.3eV and related ODLTS feature near 450K. However, the total concentration of all deep traps was much lower than necessary to explain the observed decrease in net donor density upon irradiation, and the proton irradiated films showed a nonuniform distribution of donor densities with concentrations greatly decreased toward the surface.