A material is considered n-type dopable if the most favorable native acceptor defect has high formation energy. In such a case, electrons generated by a sufficiently soluble donor dopant are not compensated by the holes created by the native acceptor. In other words, a "killer" acceptor defect is absent under the chosen condi-tions. Accordingly, an n-type dopability window (DE n ) may be defined at the CBM (Figure ), where a large positive DE n indicates a highly n-type dopable material while a negative window would suggest difficulty in n-type doping. Similarly, a p-type dopability window (DE p ) is set by the formation energy of the favorable native donor defect at the VBM and provides a measure of the potential for p-type doping.