Tunable band gap of AlN, GaN nanoribbons and AlN/GaN nanoribbon heterojunctions: A first-principle study

•Electronic structures of AlN and GaN nanoribbons were studied.•Band gap as a function of ribbon widths were investigated.•(AlN)x/(GaN)1−x nanoribbon heterojunctions were modeled.•A tunable band gap was observed by changing the Al (or Ga) concentration in the heterojunctions.

We systematically investigate the electronic structure of AlN, GaN and (AlN)x/(GaN)1−x nanoribbon heterojunctions by employing first-principle calculations. The band gaps of both AlN and GaN ribbons decrease monotonically with the increase of the widths, and the ribbons with armchair edges are direct band gap semiconductors while the zigzag ones are indirect. Interestingly, the band gaps of (AlN)x/(GaN)1−x nanoribbon heterojunctions are closely associated with the AlN/GaN ratios and increase monotonically with the increase of the AlN concentration. The flexible tunability of the band gap in these nanostructures may be widely applied to future optoelectronic devices.