Effects of high-energy electron irradiation on blue luminescence of unintentionally doped GaN heterostructure

Abstract

The unintentionally doped epitaxial GaN was grown on (0001) sapphire by metal organic chemical vapor deposition (MOCVD). The effects of 2MeV electron irradiation with the doses of 1×1015/cm2 and 5×1015/cm2 on the GaN epilayers were investigated by photoluminescence (PL) and Rutherford backscattering spectroscopy (RBS). The blue luminescence (BL) from the GaN epitlayers decreases significantly after the dose of 1×1015/cm2 electron irradiation. This is attributed to complex formation of BL-related defects with other point defects. On the contrary, the BL intensity from the GaN epilayers subjected to electron irradiation with the dose of 5×1015/cm2 increases beyond the BL intensity from the low-dose irradiated one. It is deduced that the surplus gallium vacancies in 1− charge state (VGa1-) could lead to the BL intensity rebounding as electron irradiation damage accumulated.