Towards silicon nanocrystals based solar cells: Morphological properties and conduction phenomena

In this work, we present the fabrication and the structural and electrical characterization of quantum confined silicon nanodots for advanced 3^rd generation photovoltaic cells. Silicon permits its bandgap control by forming quantum confined nanocrystals in SiO₂ (diameter <; 10 nm) and allowing a bandgap of more than that of the bulk (1.1 eV). We examine the properties of such films of SiO₂ with embedded silicon nanocrystals (nc-Si) of diameter ≈ 5 nm. Techniques like GIXRD, HRTEM, FTIR, XPS and spectroscopic ellipsometry have been used to investigate the film structure, size and distribution of the nanocrystals. Contrary to expectations from a largely dielectric material, significant conduction has been observed in our nc-Si embedded SiO₂ film. This conduction, likely to be via the nanodots, is a promising result for integration into photovoltaic devices.