Photoluminescence and Optical Characterizations of Nanocrystalline Silicon Dots Formed by Plasma-Enhanced Chemical Vapor Deposition

Abstract

We report the photoluminescence (PL) and optical properties of nanocrystalline silicon (nc-Si) dots grown on thermally grown SiO2 by rf (13.56 MHz) plasma-enhanced chemical vapor deposition of tetrachlorosilane (SiCl4) and H2. The nc-Si dots fabricated at temperatures of ∼120°C show relatively strong emissions in the visible range of 1.3–2.0 eV. The PL peak energy systematically shifts to lower energy from 1.75 eV to 1.45 eV by increasing the deposition period, which is due to the size distribution of nc-Si dots. On the other hand, the PL efficiency depends on both the deposition period and subsequent oxidation methods such as the storage in air, and pure water and HCl acid rinse treatments. The PL efficiency is markedly improved by the pure water rinse rather than by the storage in air, although a prolonged water rinse deteriorates the PL efficiency. On the other hand, the HCl acid rinse results in marked enhancement of PL efficiency with high stability. The effects of deposition conditions and surface treatment on the PL efficiency, stability and optical properties are demonstrated.