2 MeV proton radiation damage studies of gallium nitride films through low temperature photoluminescence spectroscopy measurements

Gallium nitride (GaN) thin film samples were grown by ammonia-molecular beam epitaxy, Through room temperature transport measurements, electron mobilities of 560 cm(2)/Vs were observed for layers with a carrier density of 1.5 x 10(17) cm(-3). Room temperature photoluminescence (PL) spectroscopy revealed the bound exciton transition at 363.0 nm and a weak yellow emission whose intensity was sample dependent. At 22K, the main photoluminescence signal sharpened, shifted to 356.9 mn (3.474 eV), and the maximum intensity increased by a factor of one hundred; the intensity of the yellow emission decreased. The samples were irradiated at room temperature with 2 MeV protons at fluences of 10(9), 10(10), 10(11), 10(12), 10(13), 10(14), 10(15), and 10(16) cm(-2). The intensity changes mere within experimental error up to 10(13) cm(-2). The drop in intensity of the bound exciton transition was 16% at 10(14) cm(-2) and 99% at 10(15) cm(-2). The radiation damage constant associated with the main PL peak at 3.474 eV in GaN is (1.4 +/- 0.3) x 10(-13) cm(2), compared with (4 +/- 1) x 10(-11) cm(2) associated with the main PL peak at 1.492 eV in GaAs. For photonic applications, GaN is more robust than GaAs with respect to displacement damage.