Preparation and photoluminescence of Eu-doped GaN films by radio frequency magnetron sputtering method

The red-luminescent Eu-doped GaN film has been prepared on both sapphire and GaN/sapphirc substrates by the conventional RF magnetron sputtering method using a compound powder target (GaN + EuN), N-2 sputtering gas and subsequent annealing in NH3. The GaN:Eu layers exhibited a red sharp photoluminescence (PL) line at 622 nm due to D-5(0)-F-7(2) transition of Eu3+ ions together with series of narrow PL lines: D-5(1)-F-7(1) (540 nm), D-5(0)-F-7(1) (580-600 nm), and D-5(0)-F-7(3) (665 nm). Dependence of Eu-related PL on the growth condition is described: Eu-doping level (EuN in target), substrate temperature (T-s), growth time, and annealing temperature (T-a). The optimum conditions for luminescent GaN: Eu are: (i) the Eu of 2 mol% in target, (ii) T-s at 400-450 degrees C, and (iii) T-a at 1000 degrees C for 2 hours. Improvements in intensity and reproducibility of Eu-related PL have been attained by: (i) the increase of growth time, (ii) the use of undoped GaN buffer layer, (iii) the improvement of the target quality, and (iv) the use of the MOVPE grown GaN/Al2O3 template. Preliminary studies of various PL properties are described: the fine structure in PL spectra, PL decay characteristics, temperature dependence and photoluminescence excitation spectrum (PLE). The PL results are discussed in comparison with those in the GaN:Eu grown by other methods in literature. (c) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.