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

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 SiN x, Al 2 O 3, and SiO 2 . Furthermore, their passivation mechanisms are investigated by photoluminescence (PL), time-resolved PL. Contrary to SiO 2 passivation, the SiN x and Al 2 O 3 passivation nanowires demonstrate notable improvements in emission intensity. Most essentially, all experimental findings are consilience with the physical model that the deposition of dielectric layers effectively alter the surface states of nanowires resulting a weakening or strengthen in band bending near the surface. Our systematic studies on passivation of nanowires can provide strategies for optimizing the performance of nanowire-based optoelectronic applications.