Polarization memory effect in the photoluminescence of nc-Si-SiOx light-emitting structures.

Katerina Michailovska,Ivan Indutnyi,Petro Shepeliavyi,Mykola Sopinskyy

doi:10.1186/s11671-016-1496-4

Katerina Michailovska, Ivan Indutnyi + Show 2 more

Open Access

https://doi.org/10.1186/s11671-016-1496-4

Copy DOI

Abstract

The polarization memory (PM) effect in the photoluminescence (PL) of the porous nc-Si−SiOx light-emitting structures, containing nanoparticles of silicon (nc-Si) in the oxide matrix and passivated in a solution of hydrofluoric acid (HF), has been investigated. The studied nc-Si−SiOx structures were produced by evaporation of Si monoxide (SiO) powder in vacuum and oblique deposition on Si wafer, and then the deposited silicon oxide (SiOx) films were annealed in the vacuum at 975 °C to grow nc-Si. It was found that the PM effect in the PL is observed only after passivation of nanostructures: during etching in HF solution, the initial symmetric nc-Si becomes asymmetric elongated. It was also found that in investigated nanostructures, there is a defined orientational dependence of the PL polarization degree (ρ) in the sample plane which correlates with the orientation of SiOx nanocolumns, forming the structure of the porous layer. The increase of the ρ values in the long-wavelength spectral range with time of HF treatment can be associated with increasing of the anisotropy of large Si nanoparticles. The PM effect for this spectral interval can be described by the dielectric model. In the short-wavelength spectral range, the dependence of the ρ values agrees qualitatively with the quantum confinement effect.

Highlights

Thin-film structures containing nanoparticles of silicon embedded in the silicon oxide (SiOx) matrix attract the attention of many researchers, because of their promising applications in advanced electronic and optoelectronic devices [1,2,3,4]
The hydrofluoric acid (HF) treatment of the samples is accompanied by a gradual change in the emission spectra and their polarization properties
With the further decrease of the nanoparticles of silicon (nc-Si) size, i.e., in the short-wave region of the PL band, the increase of ρ with the decrease of wavelength, as in porous silicon, agrees qualitatively with the quantum-confined nanostructure model in which the degree of polarization increases with decreasing nanostructure size [21, 22]

Summary

Introduction

Thin-film structures containing nanoparticles of silicon (nc-Si) embedded in the silicon oxide (SiOx) matrix attract the attention of many researchers, because of their promising applications in advanced electronic and optoelectronic devices [1,2,3,4]. Effective etching and passivation takes place in porous nc-Si−SiOx structures that are formed by oblique deposition of Si monoxide (SiO) in Michailovska et al Nanoscale Research Letters (2016) 11:277 vacuum and the subsequent high-temperature annealing of the obtained SiOx layer [12,13,14]. These layers have a porous columnar structure with oxide nanocolumns inclined at a certain angle to the sample surface. Polarized emission of these nanostructures may have potential uses as backlight for flat-panel displays [16] and as a biological labeling [17]

Methods

Results

Conclusion