Tuning Structural Properties and Interwall Spacing of Double‐Walled GaN Nanotubes

Abstract

The structural, stability, and electronic properties of double-walled GaN nanotubes are investigated based on density functional theory with the SIESTA code. The computations are done on the zigzag (5,0)@(m,0) and (6,0)@(m,0) with m = 11–18 and the armchair (4,4)@(m,m) and (5,5)@(m,m) double-walled GaN nanotubes with m = 7–15. The calculated binding and formation energies reveal that the armchair and zigzag double-walled GaN nanotubes with chirality differences of 7, (m,m)@(m + 7, m + 7) and 8, (m,0)@(m + 8,0) and interlayer spacing of about 6.4 and 4.2 Å are the best favorable nanotubes, respectively. Analyzing the electronic structures reveals that all considered armchair and zigzag nanotubes are semiconductors with indirect and direct bandgap, respectively. Furthermore, it is concluded that with increasing diameters of the tubes and the spaces between walls, the value of the bandgap increases, and the change process is almost constant at larger distances between the walls. Also, compared to single-walled nanotubes, double-walled GaN nanotubes have a narrower bandgap. Future empirical investigations can definitely benefit from the implications of this research.