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/sapphire substrates by the conventional RF magnetron sputtering method using a compound powder target (GaN + EuN), N 2 sputtering gas and subsequent annealing in NH 3 . The GaN:Eu layers exhibited a red sharp photoluminescence (PL) line at 622 nm due to 5 D 0 – 7 F 2 transition of Eu 3+ ions together with series of narrow PL lines: 5 D 1 – 7 F 1 (540 nm), 5 D 0 – 7 F 1 (580–600 nm), and 5 D 0 – 7 F 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 °C, and (iii) T a at 1000 °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/Al 2 O 3 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. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)