【International Papers】Electron irradiation effects on the optical properties of Hf and Zn doped β-Ga₂O₃

      Researchers from the Washington State University have published a dissertation titled " Electron irradiation effects on the optical properties of Hf and Zn doped β-Ga₂O₃ " in Journal of Applied Physics.

Abstract

      Optical and electrical properties of Hf- and Zn-doped β-Ga₂O₃ samples, which are n-type and insulating, respectively, were altered via high-energy electron irradiation at 2.5 or 0.5 MeV. The β-Ga₂O₃:Hf samples irradiated with 2.5 MeV electrons experienced a color change from blue to yellow and a large drop in conductivity, attributed to the creation of gallium vacancies, which compensate donors. This irradiation resulted in the absence of free carrier absorption and the presence of Cr³⁺ photoluminescence (PL). PL mapping prior to irradiation revealed optically active ZnO precipitates that formed during the growth of β-Ga₂O₃:Zn. These precipitates have a 384 nm (3.23 eV) stacking fault emission in the core; in the outer shell of the precipitate, the PL blue-shifts to 377 nm (3.29 eV) and a broad defect band is observed. After 0.5 MeV electron irradiation, the defect band broadened and increased in intensity. The blue PL band (435 nm) of β-Ga₂O₃ was enhanced for both Hf- and Zn-doped samples irradiated with 0.5 MeV. This enhancement is correlated with an increase in oxygen vacancies.

FIG. 1.(a) Image showing color change of Hf-doped β-Ga₂O₃ as-grown, 0.5 MeV, and 2.5 MeV irradiated samples. (b) UV-Vis transmission spectra of the samples.

FIG. 2. (a) Low-temperature IR absorbance spectra of Hf-doped β-Ga₂O₃ samples post-electron irradiation with 0.5 and 2.5 MeV energy. The absorbance was calculated using a blank spectrum (no sample) as the baseline. (b) Spectrum of the 2.5 MeV irradiated sample showing an O–H vibrational peak. (c) Spectrum of the 2.5 MeV irradiated sample showing Ir⁴⁺ electronic transitions.

Original link:https://doi.org/10.1063/5.0196824