Are fluorinated BN nanotubes n-type semiconductors?
  The structural and electronic properties of fluorine (F)-doped BN nanotubes (BNNTs) are studied using density functional methods. Our results indicate that F atoms prefer to substitute N atoms, resulting in substantial changes of BN layers. However, F substitutional doping results in no shallow impurity states. The adsorption of F atoms on B sites is more stable than that on N sites. BNNTs with adsorbed F atoms are p-type semiconductors, suggesting the electronic conduction in F-doped multiwalled BNNTs with large conductivity observed experimentally might be of p-type due to the adsorbed F atoms, but not n-type as supposed before. 
H. J. Xiang, Jinlong Yang, J. G. Hou, and Qingshi Zhu