Electronic and optical properties of GaN/AlN core–shell nanowires

Abstract

The electronic and optical properties of GaN/AlN core–shell nanowires (NWs) with different core–shell ratios are studied by means of density functional theory (DFT). The results show that as the GaN core structure increases (the AlN shell remains unchanged), the band gap of NWs decreases. In contrast, with the increase of AlN shell (GaN nucleus remains unchanged), the band gap almost remains unchanged. That is to say the adjustment capability of core–shell ratio for the band gap of GaN/AlN core–shell NWs with the same diameter of GaN core degenerates, and the band gap of which are mainly controlled by GaN core. Ga–N bond and Al–N bond show a strong ionic property because of the electronegativity of N is strong over Ga and Al. In addition, the calculated results of the real part [Formula: see text] and the imaginary parts [Formula: see text] with photon energy indicate that the storage capability and loss of the NWs to electric field energy are different with the content of AlN. The four structured NWs reflect electromagnetic waves as conductor in a high frequency ultraviolet range. The results are valuable for the design of GaN/AlN core–shell NWs optoelectronic nanodevices and the research of other core–shell NWs heterostructures.