Diffusion mechanism and photoluminescence of erbium in GaN Yi-Sheng Ting a , Chii-Chang Chen b, * , Chien-Chieh Lee a , Gou-Chung Chi a , Tapas Kumar Chini c , Purushottam Chakraborty c , Hui-Wen Chuang d , Jian-Shihn Tsang d , Cheng-Ta Kuo d , Wen-Chung Tsai d , Shu-Han Chen e , Jen-Inn Chyi e a Department of Physics, National Central University, 320 Jung-Li, Taiwan b Institute of Optical Sciences, National Central University, 320 Jung-Li, Taiwan c Saha Institute of Nuclear Physics, I/AF, Bidhannagar, Calcutta, 700 064, India d Advanced Epitaxy Technology, No.119 Kuangfu N. Road, 303 Hsinchu Industrial Park, Taiwan e Department of Electrical Engineering, National Central University, Jung-Li, Taiwan Received 2 June 2002; received in revised form 12 February 2003; accepted 3 March 2003 Abstract Erbium has been diffused into GaN for the first time. A weak spontaneous emission is observed in the photo- luminescence spectra after the diffusion process during 168 h at 800 °C under N 2 atmosphere. The diffusion coefficient of erbium in GaN is obtained in Arrenhius expression to be D ¼ 1:8  1:3  10 12 expð1  0:4 eV=kT Þ cm 2 /s. The result shows that the Er diffusion mechanism might be an interstitial-assisted process. The luminescence characteristics of the Er-diffused GaN is compared with the Er-implanted GaN. The methods to enhance the emission intensity of the Er-diffused GaN are discussed. Ó 2003 Elsevier B.V. All rights reserved. PACS: 71.20.Eh; 78.55.Cr; 85.40.Ry; 77.84.Bw Keywords: GaN; Rare earth; Diffusion; Ion implantation Rare-earth doped GaN is a promising material because of its potential applications as compact and multi-color light-emitting devices in visible and infrared regions [1–5]. GaN-based (III-nitride) semiconductors, because of their wide band gaps, are expected to be ideal host for Er 3þ ions to emit near-infrared (1.54 lm) photoluminescence (PL) useful for optical fiber communications. Two methods have been performed to achieve rare- earth element doping. Dy, Tm, and Er were doped into GaN by ion implantation [6,7]. In situ doping [7–9] has shown a more efficient luminescence emission, since the Er concentration can be uni- formly doped in bulk GaN and the luminescence intensity depends on the Er concentration in GaN [10]. Although there are reports on the observation of 1.54 lm luminescence from Er-implanted GaN, * Corresponding author. Tel.: +886-3-4227151x5257; fax: +886-3-425-2897. E-mail address: trich@ios.ncu.edu.tw (C.-C. Chen). 0925-3467/$ - see front matter Ó 2003 Elsevier B.V. All rights reserved. doi:10.1016/S0925-3467(03)00086-7 Optical Materials 24 (2003) 515–518 www.elsevier.com/locate/optmat