Si nanoparticle interfaces in Si/SiO2 solar cell materials

TL;DR

This study investigates Si nanoparticle interfaces in Si/SiO2 solar cell materials using positron annihilation spectroscopy and photoluminescence, revealing interface states and effects of annealing on optical properties.

Contribution

It identifies and characterizes two positron-trapping interface states in Si/SiO2 nanostructures and examines how annealing influences these states and photoluminescence.

Findings

Two interface states observed after annealing at 1100°C.

Annealing in N2 with 5% H2 reduces positron trapping.

Photoluminescence is enhanced after annealing.

Abstract

Novel solar cell materials consisting of Si nanoparticles embedded in SiO2 layers have been studied using positron annihilation spectroscopy in Doppler broadening mode, and photoluminescence. Two positron-trapping interface states are observed after high temperature annealing at 1100{\deg}C. One of the states is attributed to the (SiO2/Si bulk) interface and the other to the interface between the Si nanoparticles and SiO2. A small reduction in positron trapping into these states is observed after annealing the samples in N2 atmosphere with 5% H2. Enhanced photoluminescence is also observed from the samples following this annealing step.