Nitrogen and fluorine doped ZrO$_2$: A promising $p$-$n$ junction for   ultraviolet light-emitting diode
  In the present work we study the effect of nitrogen (N) and fluorine (F) doping in the electronic properties of ZrO$_2$ by using \emph{ab initio} electronic structure calculations. Our calculations show the importance of on-site Coulomb correlation in estimating the correct band gap of ZrO$_2$. The N and F doping provide hole and electron type impurity states in the band gap closer to the top of the valance band and bottom of the conduction band, respectively. The formation of such impurity states may be exploited in fabricating a $p$-$n$ junction expected to be useful in making an ultraviolet light-emitting diode. 
Sudhir K. Pandey
cond-mat.mtrl-sci