RBS/c and PL studies of ZnO implanted with Pr ions

High-quality ZnO epitaxial layers deposited by Atomic Layer Deposition were implanted at room temperature with 150 keV Pr3+ions to fluence of 1x1015 and 2x1015. Two different types of annealing on as implanted samples were performed: rapid thermal annealing (RTA) and flash lamp annealing (FLA). Crystalline quality, damage recovery and Yb lattice site location were evaluated by the Channeling Rutherford Backscattering Spectrometry (RBS/c). The optical properties were studied by photoluminescence (PL). Upon annealing defects recovery has been observed. After RTA the return of Zn atoms to their substitutional sites produces displacement RE atoms into interstitial positions. The increase of RTA temperature and time leads to enhanced out-diffusion of RE atoms. Consequently, better recovery of the crystal structure is accompanied by lower photoluminescence (PL) efficiency. The FLA precludes the RE-atom surface segregation. The substitutional fraction of Pr ions is higher than after RTA with the same structure recovery, but PL intensity from Pr3+ is lower. This suggests that the substitutional RE atoms are preferentially in the 2+ state. Acknowledgments: The work was supported by the NCBiR (Poland) project PBS2/A5/34/2013 and by the EU 7th FP project REGPOT-CT-2013-316014 (EAgLE), by the Polish Ministry of Science and Higher Education (3418/SPIRIT/2015/0) and by the Helmholtz Zentrum Dresden-Rossendorf (HZDR) in a frame of the program Access to Infrastructure (15100222-ST and 16000696-ST).