Optical degradation and defect activation in MOVPE grown near surface InGaN quantum wells under low energy electron beam irradiation

In this paper, we present out studies on low energy electron beam induced optical degradation and defect activation of indium gallium nitride quantum wells. A clear reduction in band-to-band photoluminescence of metal organic vapor phase epitaxy grown III-nitride films and quantum well structures treated with low energy electron beam has been found before. It has been proposed that the photoluminescence degradation is caused by activation of in-grown gallium vacancies and hydrogen complexes. The electron beam dissipation profiles are studied in order to obtain more information on the possible vacancy activation mechanism. Monte-Carlo simulations and cubic polynomial approximation of the Bethe-Bloch formula are compared with measured photoluminescence degradation. Our experiments suggests that the reason for photoluminescence decrease is not only dependent on the total energy dissipation density of the electron beam, but on the momentary dissipation density in the irradiated area. Thus, it seems that the degradation probably results from multicollision events. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)