In situ luminescence measurements of GaN/Al2O3 film under different energy proton irradiations

Abstract

Ion beam-induced luminescence (IBIL) experiments were performed to investigate the in situ luminescence of GaN/Al2O3 at varying ion energies, which allowed for the measurement of defects at different depths within the material. The energies of H+ were set to 500 keV, 640 keV and 2 MeV, the Bragg peaks of which correspond to the GaN film, GaN/Al2O3 heterojunction and Al2O3 substrate, respectively. A photoluminescence measurement at 250 K was also performed for comparison, during which only near band edge (NBE) and yellow band luminescence in the GaN film were observed. The evolution of the luminescence of the NBE and yellow band in the GaN film was discussed, and both exhibited a decrease with the fluence of H+. Additionally, the luminescence of F centers, induced by oxygen vacancies, and Cr3+, resulting from the 2E →4A2 radiative transition in Al2O3, were measured using 2 MeV H+. The luminescence intensity of F centers increases gradually with the fluence of H+. The luminescence evolution of Cr3+ is consistent with a yellow band center, attributed to its weak intensity, and it is situated within the emission band of the yellow band in the GaN film. Our results show that IBIL measurement can effectively detect the luminescence behavior of multilayer films by adjusting the ion energy. Luminescence measurement can be excited by various techniques, but IBIL can satisfy in situ luminescence measurement, and multilayer structural materials of tens of micrometers can be measured through IBIL by adjusting the energy of the inducing ions. The evolution of defects at different layers with ion fluence can be obtained.