Introduction and recovery of point defects in electron-irradiated ZnO

作者：Filip Tuomisto, Kimmo Saarinen, David C. Look, Gary C. Farlow · 发表于：Physical Review B · 年份：2005 · DOI：10.1103/physrevb.72.085206 · 被引用次数：320 · 研究领域：ZnO doping and properties、Ga2O3 and related materials、Copper-based nanomaterials and applications

We have used positron annihilation spectroscopy to study the introduction and recovery of point defects in electron-irradiated $n$-type ZnO. The irradiation (${E}_{\mathrm{el}}=2\phantom{\rule{0.3em}{0ex}}\mathrm{MeV}$, fluence $6\ifmmode\times\else\texttimes\fi{}{10}^{17}{\mathrm{cm}}^{\ensuremath{-}2}$) 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 $[{V}_{\mathrm{Zn}}]\ensuremath{\simeq}{c}_{\mathrm{ion}}\ensuremath{\simeq}2\ifmmode\times\else\texttimes\fi{}{10}^{16}{\mathrm{cm}}^{\ensuremath{-}3}$. The O vacancies are introduced at a 10-times-larger concentration $[{V}_{\mathrm{O}}]\ensuremath{\simeq}3\ifmmode\times\else\texttimes\fi{}{10}^{17}{\mathrm{cm}}^{\ensuremath{-}3}$ 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...