First-Principles Band-Structure Calculations of p- and n-Type Substitutional Impurities in Zinc-Blende Aluminum Nitride

The tight-binding linearized muffin-tin orbitals technique is used in the atomic-sphere approximation (TB-LMTO-ASA) to study electronic properties of zinc-blende aluminum nitride (c-AlN) doped with various substitutional impurities. p-type impurities include Mg and Zn substituted at Al sites of the host lattice, and C and Si atoms substituted at N sites. The n-type impurities considered here include C and Si at Al sites and O substituted at N sites. To mitigate the shortcomings of the local density approximation (LDA) in accurately predicting energy differences between impurity bands and the bottom of the conduction band, the predictions of Zn and O substitutional impurities are compared with experimental results for these impurities. Based on these electronic-structure comparisons, we suggest that Mg is the best candidate among the four elements investigated as p-type dopants, and that Si is better than C for n-type doping.