Optimizing n -type doping of ZnGeN2 and ZnSiN2

In order for the wide-band-gap Zn-IV-nitrides to find applications in power electronics or optoelectronics, controlled $n$-type doping is required. We systematically explore group-V and group-VI dopants that can act as donors in ${\mathrm{ZnGeN}}₂$ and ${\mathrm{ZnSiN}}₂$. We address compensation by native acceptors as well as self-compensation by formation of $DX$ centers. For ${\mathrm{ZnGeN}}₂$, we find that ${\mathrm{S}}_{\mathrm{N}}$, ${\mathrm{Se}}_{\mathrm{N}}$, ${\mathrm{P}}_{\mathrm{Ge}}$, and ${\mathrm{As}}_{\mathrm{Ge}}$ act as shallow donors. ${\mathrm{P}}_{\mathrm{Ge}}$ has the lowest formation energy and can be used to reach carrier concentrations up to $n=1.3\ifmmode\times\else\texttimes\fi{}{10}¹⁹\phantom{\rule{4pt}{0ex}}{\mathrm{cm}}^{\ensuremath{-}3}$. ${\mathrm{P}}_{\mathrm{Si}}$ acts as a shallow donor in ${\mathrm{ZnSiN}}₂$; however, because of strong compensation from native acceptors, we find that ${\mathrm{ZnSiN}}₂$ cannot be doped $n$ type.