Introduction and recovery of point defects in electron-irradiated ZnO

F. Tuomisto, K. Saarinen, D. C. Look, and G. C. Farlow
Phys. Rev. B 72, 085206 – Published 3 August 2005

Abstract

We have used positron annihilation spectroscopy to study the introduction and recovery of point defects in electron-irradiated n-type ZnO. The irradiation (Eel=2MeV, fluence 6×1017cm2) was performed at room temperature, and isochronal annealings were performed from 300 to 600 K. In addition, monochromatic illumination of the samples during low-temperature positron measurements was used in identification of the defects. We distinguish two kinds of vacancy defects: the Zn and O vacancies, which are either isolated or belong to defect complexes. In addition, we observe negative-ion-type defects, which are attributed to O interstitials or O antisites. The Zn vacancies and negative ions act as compensating centers and are introduced at a concentration [VZn]cion2×1016cm3. The O vacancies are introduced at a 10-times-larger concentration [VO]3×1017cm3 and are suggested to be isolated. The O vacancies are observed as neutral at low temperatures, and an ionization energy of 100 meV could be fitted with the help of temperature-dependent Hall data, thus indicating their deep donor character. The irradiation-induced defects fully recover after the annealing at 600 K, in good agreement with electrical measurements. The Zn vacancies recover in two separate stages, indicating that the Zn vacancies are parts of two different defect complexes. The O vacancies anneal simultaneously with the Zn vacancies at the later stage, with an activation energy of EV,Om=1.8±0.1eV. The negative ions anneal out between the two annealing stages of the vacancies.

  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
5 More
  • Received 6 April 2005

DOI:https://doi.org/10.1103/PhysRevB.72.085206

©2005 American Physical Society

Authors & Affiliations

F. Tuomisto* and K. Saarinen

  • Laboratory of Physics, Helsinki University of Technology, P.O. Box 1100, 02015 TKK, Finland

D. C. Look

  • Semiconductor Research Center, Wright State University, Dayton, Ohio 45435, USA and Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson AFB, Ohio 45433, USA

G. C. Farlow

  • Physics Department, Wright State University, Dayton, Ohio 45435, USA

  • *Electronic address: filip.tuomisto@tkk.fi

Article Text (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand
Issue

Vol. 72, Iss. 8 — 15 August 2005

Reuse & Permissions
Access Options

Authorization Required


×
×

Images

×

Sign up to receive regular email alerts from Physical Review B

Log In

Cancel
×

Search


Article Lookup

Paste a citation or DOI

Enter a citation
×