Red light emission by photoluminescence and electroluminescence from Eu-doped GaN

Visible light emission has been obtained at room temperature by photolumine scence (PL) and electroluminescence (EL) from Eu-doped GaN thin films. The GaN was grown by molecular beam epitaxy on Si substrates using solid source s (for Ga and Eu) and a plasma source for N-2. X-ray diffraction shows the GaN:Eu to be a wurtzitic single crystal film. Above GaN band gap photoexcit ation with a He-Cd laser at 325 nm resulted in strong red emission. Observe d Eu3+ PL transitions consist of a dominant narrow red line at 621 nm and s everal weaker emission lines were found within the green through red (543 t o 663 nm) range. Below band gap PL by Ar laser pumping at 488 nm also resul ted in red emission, but with an order of magnitude lower intensity. EL was obtained through use of transparent indium-tin-oxide contacts to the GaN:E u film. Intense red emission is observed in EL operation, with a spectrum s imilar to that seen in PL. The dominant red line observed in PL and EL has been identified as the Eu3+ 4f shell transition from the D-5(0) to the F-7( 2) state. (C) 1999 American Institute of Physics. [S0003-6951(99)00735-4].