Enhanced thermoelectric performance of the AlN/GaN bilayer

Improving the thermoelectric (TE) transformation efficiency has always been the focus in the TE fields. Inspired by the research progress of the predominant TE performance of graphitelike nanofilms, we constructed AlN/GaN bilayer nanofilms based on the hexagonal lattice planes along (001) surface of wurtzite (WZ) AlN and GaN bulk. By the first-principles calculation within the framework of density functional theory (DFT) combined with non-equilibrium Green's Function (NEFG) method and Landauer-Buttiker theory, the stability, the electronic structures, the TE parameters and the figure of merit ZT of AlN/GaN bilayer nanofilms are investigated and analyzed in detail. Relative to AlN and GaN monolayer, the maximum ZT of AlN/GaN bilayer is improved, which can reach 1.41 at 700 K for p-type doping. Our research provides an idea that bilayer heterojunction nanofilm has superior TE performance to that of the corresponding semiconductor monolayer.