ANALYSIS OF THE EFFECT OF SILICON QUANTUM DOT DENSITY ON THE PHOTOLUMINESCENCE SPECTRA OF SILICON DOT/SILICON DIOXIDE SUPERLATTICES

摘要

Nanocrystalline Si embedded in dielectric matrices, has attracted remarkable attention due to the potential to increase the band gap of Si due to quantum size effect. These new materials explored could be useful for improving efficiencies of solar cell, by using the tandem cell approach. In this paper, we have studied the effect of Si dot density on the photoluminescence spectra of Si dot superlattices in a SiO{sub}2 matrix. The asymmetric PL spectrum observed at room temperature can be fitted by three Gaussian bands (peaks Q, I and α). The dominant peak Q is due to the quantum confinement effect of Si quantum dot (Si QD), shifting to higher energy with decrease of dot size. The peaks I and α would likely involve the interface effect between Si QD and a-SiO{sub}2 matrix, and the localized state transitions of amorphous silicon shell, respectively. Our results indicate that the increase of the density of Si QDs which strongly influences the intense I band due to possibly increasing interface state density which bring about interface state process. This is in good agreement with the observed increase in I band intensity with increase in QD size.