Adjusting the crystal size of InSb nanowires for optical band gap energy modification

Abstract

The main objective of this paper is to demonstrate the effect of crystal size on the optical properties of InSb nanowires. Nanowires were synthesized by a template-assisted pulse electrodeposition method. The crystal size in obtained nanowires was tuned using two approaches, namely via (i) adjustment of nanowire diameter by using anodic aluminum oxide (AAO) templates with different channel diameters (i.e., 25 nm, 46 nm, and 72 nm), and (ii) annealing of nanowires at various temperatures (i.e., 623 K, 673 K, and 723 K). The morphology, crystal size, and chemical composition of nanostructures were examined using different methods of materials characterization. Finally, an effect of crystal size on the optical properties of nanowires was demonstrated. Along with increasing the annealing temperature and diameter of nanowires, an increase in crystal size and widening of band gap energy were observed. Received dependences were compared with theoretical models proposed in the literature. To explain the nature of observed widening of band gap energy, the effective energy band gap (Eg eff.), quantum effect contribution (Eg q), Burstein-Moss effect contribution (ΔEBM), and charge carrier concentration (n) were estimated for studied diameters of as-prepared and annealed nanowires.