Blue emission from Tm-doped GaN electroluminescent devices

Blue emission has been obtained at room temperature from Tm-doped GaN elect roluminescent devices. The GaN was grown by molecular beam epitaxy on Si(11 1) substrates using solid sources (for Ga and Tm) and a plasma source for N -2. Indium-tin-oxide was deposited on the GaN layer and patterned to provid e both the bias (small area) and ground (large area) transparent electrodes . Strong blue light emission under the bias electrode was observable with t he naked eye at room temperature. The visible emission spectrum consists of a main contribution in the blue region at 477 nm corresponding to the Tm t ransition from the (1)G(4) to the H-3(6) ground state. A strong near-infrar ed peak was also observed at 802 nm. The relative blue emission efficiency was found to increase linearly with bias voltage and current beyond certain turn-on levels. (C) 1999 American Institute of Physics. [S0003-6951(99)056 41-7].