Fabrication of silicon nanocrystals using sequential Au ion implantation

TL;DR

This paper presents a novel two-stage gold ion implantation method to fabricate silicon nanocrystals, demonstrating strain-free quantum-confined NCs at low annealing temperatures and growth at higher temperatures, validated by multiple characterization techniques.

Contribution

Introduces a sequential Au ion implantation technique for controlled silicon nanocrystal fabrication with detailed analysis of strain and size effects.

Findings

Strain-free silicon nanocrystals achieved at 500°C annealing.

Recrystallization leads to size growth at higher annealing temperatures.

Raman, XRD, and RBS analyses confirm size and strain states.

Abstract

Silicon nanocrystals are produced using a two-stage gold ion implantation technique. First stage implantation using low energy ions leads to the formation of an amorphous Si (a-Si) layer. A subsequent high energy Au irradiation in the second stage is found to produce strained Si NCs. An annealing at a temperature as low as 500$^o$C is seen to result in strain free NCs showing quantum confinement effects. Higher temperature annealing of the samples is found to result in growth in size from recrystallization of the a-Si matrix. Raman Scattering, X-ray diffraction (XRD) and Rutherford Backscattering spectrometry (RBS) have been used to study the effect of annealing on the samples and the size of Si NCs formed. The data could be well explained using a phonon confinement model with an extremely narrow size distribution. XRD results go in line with Raman analysis.