In situ passivation and blue luminescence of silicon clusters using a cluster beam/H2O codeposition production method

A Brewer,K Von Haeften

doi:10.1063/1.3167355

Abstract

Si clusters are produced in a gas aggregation source and fly through ultrahigh vacuum onto a cold target where they are codeposited with water vapor. Melting of the ice yields immediately a suspension of nanoparticles that emits intense, nondegrading luminescence in the blue wavelength range. Spectroscopic analysis reveals a Si/SiO core-shell structure where the luminescence stems from oxygen deficient defects. The main advantage of our production method is that it yields the luminescent Si nanoparticles in one step.

Highlights

Since the discovery of luminescence from porous silicon at room temperature3,4 twenty years ago, fabrication of devices such as silicon-based light emitting diodesRef. 5͒ and lasers6 has been achieved, and a large variety of types of photoluminescent silicon have been reported in the literature
These include nanowires and nanorods,7–13 Si/SiO, Si/SiOH sandwich, and core-shell systems,14–16 as well as Si clusters produced by laser photolysis17,18 or by Si ion implantation in silica glass
The Si clusters flew through an aerodynamic lens system35 and differential pumping stages into two UHV chambers, of which the first housed a crystal film-thickness sensorXTMmounted on a linear translation stage for moving it in and out of the beam and the second chamber housed a cold finger that could be cooled to 80 K using liquid nitrogen

Summary

Introduction

The process of light emission from materials with an indirect band gap in the bulk has attracted much interest both from a fundamental point of view and from the prospect of applications.1,2 Since the discovery of luminescence from porous silicon at room temperature3,4 twenty years ago, fabrication of devices such as silicon-based light emitting diodesRef. 5͒ and lasers6 has been achieved, and a large variety of types of photoluminescent silicon have been reported in the literature. 2. ͑Color online PL spectra recorded three hours, three days, and three months after sample preparation.

Results

Conclusion