Anion vacancies as a source of persistent photoconductivity in II-VI and chalcopyrite semiconductors

Using first-principles electronic structure calculations we identify the anion vacancies in II-VI and chalcopyrite $\mathrm{Cu}\text{\ensuremath{-}}\mathrm{III}\text{\ensuremath{-}}{\mathrm{VI}}_{2}$ semiconductors as a class of intrinsic defects that can exhibit metastable behavior. Specifically, we predict persistent electron photoconductivity ($n$-type PPC) caused by the oxygen vacancy ${V}_{\mathrm{O}}$ in $n$-ZnO, originating from a metastable shallow donor state of ${V}_{\mathrm{O}}$. In contrast, we predict persistent hole photoconductivity ($p$-type PPC) caused by the Se vacancy ${V}_{\mathrm{Se}}$ in $p\text{\ensuremath{-}}{\mathrm{CuInSe}}_{2}$ and $p\text{\ensuremath{-}}{\mathrm{CuGaSe}}_{2}$. We…

• UD
  U.S. Department of Energy
• OO
  Office of Energy Efficiency and Renewable Energy