Enhancing the luminescence yield of Cr3+ in <b> <i>β</i> </b>-Ga2O3 by proton irradiation
M. Peres, Duarte Magalhães Esteves, B. M. S. Teixeira, Júlia Zanoni, L.C. Alves, E. Alves, Luís F. Santos, X. Biquard, Zhitai Jia, Wenxiang Mu, J. Rodrigues, Н. А. Соболев, M. R. Correia, T. Monteiro, N. Ben Sédrine, K. Lorenz
Abstract
In situ ion-beam-induced luminescence measurements reveal a strong enhancement of the Cr3+ emission yield in electrically conductive chromium doped β-Ga2O3 single crystals upon proton irradiation. The observed effect can be explained based on the Fermi-level pinning caused by radiation defects. This pinning of the Fermi level activates deep carrier traps that can act as sensitizers of the Cr3+ emission. In agreement with this model, in semi-insulating samples, where the Fermi level lies deep in the bandgap, the Cr3+ emission is present already in as-grown samples, and no enhancement of its intensity is observed upon proton irradiation. The boost of the Cr3+ emission yield by irradiation, observed in conductive samples, is reversed by thermal annealing in argon at temperatures above 550 °C for 30 s. The results reveal a high potential of Cr-doped β-Ga2O3 for in situ and ex situ optical radiation detection and dosimetry.