Fabrication and characterization of luminescent silicon nanocrystal films

Abstract

This thesis aims to understand the correlation between the structures and optical properties of Si nanocrystals (NCs) formed by pulsed-laser deposition (PLD) and plasma-enhanced chemical vapor deposition (PECVD). The Si NC films deposited by PLD and PECVD show similar properties. After thermal annealing at high temperature (>1000A?C), XPS, FTIR, Raman, HRTEM, optical absorption and photoluminescence (PL) confirm the transformation of Si suboxide into Si dioxide and elemental Si, and formation of Si NCs. The red-range PL shows intensity increase after thermal and plasma annealing, peak shift with deposition gas pressure and Si concentration (Si NC size), and blueshift after oxidation. The PL transition from multiple-peak to single peak with increasing annealing temperature is closely related to the NC formation. The good agreement of PL peak energy with Si concentration and NC size from both PLD and PECVD results support that the red-range PL is due to the quantum confinement effect.