Shallow electronic states induced by prismatic stacking faults in AlN and GaN

摘要

Wurtzite materials such as AlN and GaN can exhibit prismatic stacking faults on the (1-210) plane with a stacking fault displacement vector R_D=1/2[10-11]. These faults thread in the [0001] direction and may arise in growth on the (0001) plane from the merging of independently nucleated islands. Merging islands that have different stacking sequences in the [0001] direction, for example ABAB... vs ACAC..., give rise to the faults. The formation energy of such a stacking fault in AlN is determined using first-principles total energy calculations to be 79 meV/A~2. The perturbation caused by the highly strained four-membered rings of bonds along the boundary gives rise to shallow stacking fault states 0.1 eV above the valence band maximum and 0.1 eV below the conduction band minimum. These results are compared to those obtained for GaN.