We have studied the growth and properties of GaN:As layers prepared by molecular beam epitaxy, using a plasma source for active nitrogen. We have demonstrated that arsenic doping during growth produces films showing blue emission at room temperature. The blue emission is centred at 2.6 eV and is more than a decade stronger than the band edge emission. The films are predominantly wurtzite, but with a small cubic content which exists mainly close to the substrate-epilayer interface. We have investigated the influence of growth conditions on the intensity of this blue emission. In films grown under optimum conditions, the blue emission is strong enough to be clearly visible under normal room lighting. We have also discussed the transition from As-doped GaN showing blue emission to the formation of GaN 1−x As x alloys. We have determined that for a fixed arsenic flux, increasing the N/Ga ratio leads to the formation of alloy films. Our results suggest that this materials system may have potential applications in electronic and opto-electronic devices.

Arsenic doped GaN grown by molecular beam epitaxy has been studied by room temperature photoluminescence. In addition to the wurzite band edge transition, luminescence from the cubic phase and very strong blue emission at ∼2.6 eV are observed. The intensities of the blue and the cubic band edge emissions have a power law dependence on the As2 flux. The formation of the cubic phase has been explained by the initial formation of GaAs before substitution of the As by the more reactive N. The intensity of the blue emission at room temperature of the As doped samples is more than an order of magnitude stronger than the band edge emission in undoped samples.

We have investigated the influence of the growth conditions on the intensity of blue emission at room temperature from As-doped GaN samples grown by molecular beam epitaxy. A series of As-doped GaN samples was grown at 800 • C with constant fluxes of As and gallium, but with different amounts of active nitrogen. Varying the N flux allowed us to investigate films grown from strongly Ga-rich conditions to more N-rich conditions. The blue emission increases monotonically with the nitrogen flux and is most intense in the layers grown under the most nitrogen-rich conditions. This fact suggests that As atoms incorporated into the Ga sub-lattice are responsible for the strong blue emission in As-doped GaN.

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