Adsorption of potassium on the surface of Al$_{0.5}$Ga$_{0.5}$N(0001)

The calculation for the adsorption of potassium atoms on the Al$_{0.5}$Ga$_{0.5}$N(0001) surface was performed using the density functional method. The 2D layer of Al$_{0.5}$Ga$_{0.5}$N(0001) was modeled by the Al$_{0.5}$Ga$_{0.5}$N(0001) 2 $\times$ 2 $\times$ 2 supercell containing 10 bilayers of Al$_{0.5}$Ga$_{0.5}$N. On the relaxed Al$_{0.5}$Ga$_{0.5}$N(0001) surface, the Ga atoms are located above the Al atoms. It is shown that the adsorption of K atoms at a coverage of 0.25 monolayers is preferable in the bridge position either between the surface Ga atoms or between the surface N atoms. The adsorption of potassium atoms forms a surface states zone, the electron density of which is localized near the Fermi level.