Controlling the formation of luminescent Si nanocrystals in plasma-enhanced chemical vapor deposited silicon-rich silicon oxide through ion irradiation

Abstract

The effect of ion irradiation on the formation of luminescent Si nanocrystals from silicon-rich silicon oxide ͑SRSO͒ films deposited by electron cyclotron resonance plasma-enhanced chemical vapor deposition ͑PECVD͒ whose Si content ranged from 33 to 50 at. % is investigated. As-deposited SRSO films contained a high density of irregular-shaped Si nanocrystals. Irradiating these films with 380 keV Si at room temperature to a dose of 5.7ϫ10 15 cm Ϫ2 prior to anneal at 1000°C is found to increase the luminescence intensity due to Si nanocrystals over the films. Based on the x-ray photoemission spectra and the dependence of the luminescence intensity on the irradiating ion dose, anneal time, and the silicon content of the film, we propose the destruction of pre-existing Si clusters by ion irradiation to be an important factor responsible for the observed enhancement of luminescence, and suggest that preanneal irradiation may be a viable method to control the formation of luminescent Si nanocrystals in PECVD-deposited silicon-rich silicon oxide.

Photoluminescence enhancement through silicon implantation on SRO-LPCVD films

“…The red emission has been explained according to two main models: the first one describes that the luminescence takes place in silicon nanoparticles by quantum confinement effects (QCE) [6,9] meanwhile the second model relates the PL with the presence of defects in the SiO 2 /Si-np interface [5,7,8,11,17]. It is widely accepted that when SRO films are annealed at high temperature the silicon excess agglomerates creating Si-nps or silicon compounds [3][4][5][6][7][8][9][10][11][12][13][14]. In SRO-LPCVD films with low silicon excess, a spectroscopical analysis has revealed the presence of amorphous Si-nps [11].…”

“…A spectroscopic analysis has revealed the presence of amorphous Si-nps embedded in SRO films with low silicon excess [11]. An increase of PL intensity has been already reported for thick SRO-LPCVD and SRO-PECVD films when implanted with silicon (SI-SRO) [12,13].…”

“…Therefore, many efforts have been done to improve the PL intensity in SRO films by changing the technological parameters such as silicon excess, temperature and time of anneal [6,[8][9][10][11]. However, there are a few reports on silicon implantation into SRO films, which already have silicon excess [8,12,13]. Silicon-rich oxide films with controlled and uniform silicon excess are easily deposited by LPCVD.…”

Silicon excess and thermal annealing effects on the photoluminescence of SiO2 and silicon rich oxide super enriched with siliscon implantation

“…SRO 10 did not show a significant increase with annealing temperature and time nor with implantation dose. Kim et al [13] proposed that silicon implantation into SRO-PECVD breaks down silicon compounds, promoting the homogenization of the material, especially for high silicon excess. Our results do not show such behaviour, for SRO 10 that has the highest silicon excess there is no increase of the PL.…”

Nanocrystalline Silicon Embedded in SiO Films by RF Magnetron Sputtering

“…Since the discovery of photoluminescence (PL) from porous Si, 1) many studies have been reported in recent years including the fabrication and characterization of nanocrystalline Si-based materials. [2][3][4][5][6][7][8][9][10] Despite being an indirect bandgap material, nanocrystalline Si exhibits a visible PL with a quantum efficiency of up to a few percent. Therefore, porous silicon and nanocrystalline silicon embedded in silicon suboxides have been widely studied from optical and structural points of view.…”