Extrinsic Defects in Crystalline MoO <sub/>3</sub> : Solubility and Effect on the Electronic Structure

摘要： The effect of six potential contaminants (Cu, In, Ga, Se, Sn and Zn) and five potential dopants (Ti, Mn, Sc, V and Y) on the electronic and optical properties of molybdenum oxide (MoO3) contact layers for solar cells was investigated using point defect analysis informed by density functional theory simulations. Of the contaminants investigated, Sn, In and Ga were found to be highly insoluble at all relevant temperatures and pressures, and therefore not a concern for solar cell manufacturing. Zn, Cu and Se exhibit some solubility, with the latter two appearing to introduce detrimental defect states near the valence band. This contamination can be avoided by increasing the O2 partial pressure during MoO3 deposition. Out of five potential aliovalent dopants, Sc, Ti and Y were disregarded due to their limited solubility in MoO3, while V was found to be highly soluble and Mn somewhat soluble. The effect of Mn and V doping was shown to be strongly dependent on the O2 partial pressure during deposition with a high pO2 favoring the formation of substitutional defects (potentially beneficial in the case of Mn doping due to the addition of defects states near the conduction band) while low pO2 favors interstitial defects.