Doping of chalcopyrites by hydrogen

First-principles total-energy calculations for hydrogen impurities in $CuInSe2$ (CIS) and $CuGaSe2$ (CGS) show that $H+$ takes up the Cu–Se bond center position, whereas $H0$ and $H−$ take up tetrahedral interstitial site next to In (in CIS) or Ga (in CGS). Hydrogen creates a negative-U center (i.e., $H0$ is never stable), with a $(+/−)$ transition level at $Ec−0.39 eV$ in CIS, and $Ec−0.57 eV$ in CGS. However, once combined with the $2VCu−+IIICu2+$ complex, hydrogen forms shallower centers with transition levels at $Ec−0.15 eV$ in CIS, and $Ec−0.39 eV$ in CGS. We conclude that hydrogen could convert CIS to $n$ type, but not CGS.