Electroluminescence generated by a metal oxide semiconductor light emitting diode (MOS-LED) with Si nanocrystals embedded in SiO₂layers by ion implantation

Abstract

Electroluminescence (EL) and photoluminescence (PL) measurements were conducted on Si-implanted SiO 2 layers as a function of process and measurement parameters. Measurable light emission was observed from the metal oxide semiconductor light emitting diode (MOS-LED) when holes are injected from the substrate. It was shown that major PL and EL emissions have the same origin. However, two important differences were observed between EL and PL spectra. The first one is the light emission from the Si substrate due to the recombination of electrons supplied by the front contact and holes that were accumulated in the inversion region at the substrate/SiO 2 interface. This might be a factor reducing the contribution of Si nanocrystals to the EL emission of the MOS-LED structure as a result of decrease in the number of holes in the inversion layer. The second difference is that EL emission peaks stay at a slightly higher energy than PL peaks. It was observed that the EL peak shifts towards the PL peak with increasing bias voltage. This behaviour is explained by considering the size distribution of nanocrystals formed by ion implantation.

Structure and Properties of Nanoparticles Formed by Ion Implantation

“…The emission dynamics follow the stretched exponential function with characteristic decay times of several tens to hundreds of microseconds and an exponent, β, of ∼0.7. Si nanocrystals produced by implantation of silicon into SiO 2 have potentially attractive properties with respect to possible siliconbased lasers [36,37], light-emitting diodes [38,39], and nonvolatile memory [40,41]. Optical gain has been reported in ion-implanted silicon nanocrystal composites [42,43].…”

Visible electroluminescence on FTO/thin SRO/n-Si structures

“…EL emission was collected in the range of 300-900 nm with the Fluoromax-3 spectrofluorometer controlled by computer. conductive paths (created by adjacent Si-nPs) activate the charge flow through the SRO films [26]. In general, there is a decrease of the current as Ro is increased, this means SRO samples are less conductive as Si excess is reduced.…”

Influence of nanocrystal distribution on electroluminescence from Si+-implanted SiO 2 thin films

“…[10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] Strong photoluminescence in the range from red to blue has been observed from Si + -implanted SiO 2 films by a lot of research groups although the mechanism of the luminescence is not exclusively attributed to the quantum confinement effect of the nc-Si embedded in SiO 2 . [10][11][12][13][14][15][16][17][18][21][22][23][24][25] Recently, visible electroluminescence from Si + -implanted SiO 2 films has also been demonstrated. [16][17][18][22][23][24] Even a possibility of electrically driven ultraviolet light emission from Si + -implanted SiO 2 films was predicted.…”

“…[10][11][12][13][14][15][16][17][18][21][22][23][24][25] Recently, visible electroluminescence from Si + -implanted SiO 2 films has also been demonstrated. [16][17][18][22][23][24] Even a possibility of electrically driven ultraviolet light emission from Si + -implanted SiO 2 films was predicted. 22 In the most studies focused on the luminescence properties of the nc-Si embedded in an oxide matrix, the authors employed silica glass or SiO 2 films as thick as hundreds of nanometers.…”

“…22 In the most studies focused on the luminescence properties of the nc-Si embedded in an oxide matrix, the authors employed silica glass or SiO 2 films as thick as hundreds of nanometers. [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] The thick oxide films are not suitable to fabricate efficient light emitting devices, because a higher oxide thickness indicates a poorer carrier injection. In practical, in order to achieve efficient carrier injection into the Si + -implanted layers and make EL intensity strong enough, SiO 2 thin films less than 100 nm must be employed as the base material for Si ion implantation.…”