The influence of arsenic incorporation on the optical properties of As-doped GaN films grown by molecular beam epitaxy using arsenic tetramers

We have studied the influence of the incorporation of As on the optical pro perties of As-doped GaN layers grown by plasma-assisted molecular beam epit axy (PA-MBE) using arsenic tetramers. The doping level of arsenic was deter mined by secondary ion mass spectrometry. The arsenic concentration is unif orm throughout the layers. There is a sub-linear dependence of the arsenic incorporation on the flux with a log-log slope of about 0.1. The photolumin escence from the As-doped GaN films consists of UV excitonic emission at 3. 4 eV, UV emission at 3.2 eV and a strong blue band centred at 2.6 eV. The i ntensity of the blue band centred at 2.6 eV increases more rapidly with ars enic flux than the concentration of arsenic in the bulk., and has a log-log slope of about 0.49. This suggests an approximately fourth-power dependenc e of the intensity of the blue emission on the concentration of arsenic in the GaN films.