Absolute surface energies of wurtzite (10 1 ¯ 1) surfaces and the instability of the cation-adsorbed surfaces of II-VI semiconductors

We have investigated the wurtzite (10 1 ¯ 1) planes of five semiconductors, AlN, GaN, GaAs, ZnO, and ZnS. The absolute surface energies are obtained by using a series of wedge nanowire structures. A cation-adsorbed surface reconstruction, (1 × 1)X (X is the electropositive element of the semiconductor) adlayer, is found to have dramatically low energy under the cation-rich condition for AlN and GaN. A p electron draining mechanism is proposed to explain these results. We also developed a framework to analyze the stabilization mechanism of the unneutral surfaces. It suggests that the cation-adsorbed surfaces of II-VI semiconductors should be more unstable than the anion-adsorbed surfaces.