Improving the electroluminescence of Si nanocrystal via black silicon and silver surface plasmons

Abstract

In this paper, black silicon (Si) and silver (Ag) surface plasmons were used to improve the electroluminescence (EL) intensity of silicon nanocrystals (Si-nc), and the mechanism of black Si and Ag nanoparticles enhancing the EL of Si-nc LED is analyzed. The Ag nanoparticles are introduced into Si-nc LED to generate surface plasmons. The surface plasmons radiate the local electromagnetic field, which can increase the excitation probability of Si-nc and increase the EL intensity of Si-nc LED. In addition, black silicon can improve the charge injection efficiency and light emission efficiency. The atomic force microscope (AFM) and reflectivity spectra of black silicon at different etching time, as well as the AFM and absorption spectra of Ag nanoparticles at different postannealing temperatures, were measured. Three different device structures were designed. The EL intensity of Si-nc increased by 3.2 times at the etching time of 5 minutes and increased by 4.9 times at the postannealing temperature of 200 °C, respectively. A maximal 8.5-fold EL enhancement of Si-nc was readily achieved after using the black Si as substrate and incorporating Ag surface plasmons.