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Origins of low resistivity in Al ion-implanted ZnO bulk single crystals

Journal Article · · Journal of Applied Physics
DOI:https://doi.org/10.1063/1.3600072· OSTI ID:21538445
; ;  [1];  [2];  [3]
  1. College of Engineering and Research Center of Ion Beam Technology, Hosei University, Koganei, Tokyo 184-8584 (Japan)
  2. Departments of Arts and Sciences, Osaka Kyoiku University, Kashiwara, Osaka 582-8582 (Japan)
  3. National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8568 (Japan)
The origins of low resistivity in Al ion-implanted ZnO bulk single crystals are studied by combining Rutherford backscattering spectroscopy (RBS), nuclear reaction analysis (NRA), photoluminescence (PL), and Van der Pauw methods. The Al-ion implantation (peak concentration: 2.6 x 10{sup 20}cm{sup -3}) into ZnO is performed using a multiple-step energy. The resistivity decreases from {approx}10{sup 4{Omega}} cm for un-implanted ZnO to 1.4 x 10{sup -1{Omega}} cm for as-implanted, and reaches 6.0 x 10{sup -4{Omega}} cm for samples annealed at 1000 deg. C. RBS and NRA measurements for as-implanted ZnO suggest the existence of the lattice displacement of Zn (Zn{sub i}) and O (O{sub i}), respectively. After annealing at 1000 deg. C, the Zn{sub i} related defects remain and the O{sub i} related defects disappear. The origin of the low resistivity in the as-implanted sample is attributed to the Zn{sub i} ({approx}30 meV [Look et al., Phys. Rev. Lett. 82, 2552 (1999)]). In contrast, the origin of the low resistivity in the sample annealed at 1000 deg. C is assigned to both of the Zn{sub i} related defects and the electrically activated Al donor. A new PL emission appears at around 3.32 eV after annealing at 1000 deg. C, suggesting electrically activated Al donors.
OSTI ID:
21538445
Journal Information:
Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 12 Vol. 109; ISSN JAPIAU; ISSN 0021-8979
Country of Publication:
United States
Language:
English