The growth andproperties of GaN:As layers prepared by plasma-assistedmolecular beam epitaxy

Abstract

We have studied the growth and properties of GaN:As layersprepared by molecular beam epitaxy, using a plasma source foractive nitrogen. We have demonstrated that arsenic dopingduring growth produces films showing blue emission at roomtemperature. The blue emission is centred at 2.6 eV and is morethan a decade stronger than the band edge emission. The filmsare predominantly wurtzite, but with a small cubic contentwhich exists mainly close to the substrate-epilayer interface.We have investigated the influence of growth conditions on theintensity of this blue emission. In films grown under optimumconditions, the blue emission is strong enough to be clearlyvisible under normal room lighting. We have also discussed the transition from As-doped GaN showing blue emission to theformation of GaN1-xAsx alloys. We have determinedthat for a fixed arsenic flux, increasing the N/Ga ratio leadsto the formation of alloy films. Our results suggest that thismaterials system may have potential applications in electronicand opto-electronic devices.