Silicon vacancy-type defects in as-received and 12-MeV proton-irradiated<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mn>6</mml:mn><mml:mi>H</mml:mi><mml:mo>−</mml:mo><mml:mi mathvariant="normal">SiC</mml:mi></mml:math>studied by positron annihilation spectroscopy

Abstract

Positron lifetime spectroscopy is used to detect vacancy-related defects in as-received and 12-MeV proton-irradiated $6H\ensuremath{-}\mathrm{SiC}$ crystals. We can infer from the temperature dependence of the lifetime spectra decomposition that neutral and negatively charged vacancy defects exist in crystals before and after proton irradiation at low fluence $(&lt;~4\ifmmode\times\else\texttimes\fi{}{10}^{15}{\mathrm{H}}^{+}{\mathrm{cm}}^{\ensuremath{-}2}).$ Neutral vacancies are detected after irradiation at high fluence $(&gt;~4\ifmmode\times\else\texttimes\fi{}{10}^{16}{\mathrm{H}}^{+}{\mathrm{cm}}^{\ensuremath{-}2}).$ Negatively charged ${V}_{\mathrm{Si}}$ silicon monovacancies with $202\ifmmode\pm\else\textpm\fi{}8\mathrm{ps}$ lifetime are detected at low temperature in as-received n-type $6H\ensuremath{-}\mathrm{SiC}$ and after irradiation at low fluence. Neutral ${V}_{\mathrm{S}\mathrm{i}\ensuremath{-}\mathrm{C}}$ divacancies associated with the $(225\ifmmode\pm\else\textpm\fi{}5)\ensuremath{-}\mathrm{ps}$ lifetime are produced by irradiation and dominate the positron trapping at room temperature. In addition, different types of ionic acceptors are detected. One of them acts as a strong trapping center even at room temperature.