Manipulating the Band Bending of InGaN/GaN Quantum Dots in Nanowires by Surface Passivation

Abstract

InGaN/GaN quantum dots (QD) in nanowires exhibit excellent optical properties and are promising candidates for nanoscale optoelectronic devices. However, a large amount of surface states would cause low quantum efficiency more severely than bulk materials, through not only nonradiative recombination centers but also upward band bending. Therefore, it is necessary to control the band bending effect in order to improve the quantum efficiency of QDs. In this work, quantitative measurements are carried out by ultraviolet photoelectron spectroscopy (UPS) to describe the band bending effect in InGaN/GaN QD in nanowires coated with three different dielectric layers including SiNx, Al2O3, and SiO2. Furthermore, their passivation mechanisms are investigated by photoluminescence (PL), time-resolved PL. Contrary to SiO2 passivation, the SiNx and Al2O3 passivation nanowires demonstrate notable improvements in emission intensity. Most essentially, all experimental findings are consilience with the physical model that ...