Defect versus nanocrystal luminescence emitted from room temperature and hot-implanted SiO_2 layers

摘要

Silicon nanocrystals have been synthesized in SiO_2 matrix using Si ion implantation. Si ions were implanted into 300-nm-thick SiO_2 films grown on crystalline Si at energies of 30-55 keV, and with doses of 5 X 10~15, 3 X 10~16, and 1 X 10~17 cm~-2. Implanted samples were subsequently annealed in an N_2 ambient at 500-1100 deg C during various periods. Photoluminescence spectra for the sample implanted with 1 X 10~17 cm~-2 at 55 keV show that red luminescence (750 nm) related to Si-nanocrystals clearly increases with annealing temperature and time in intensity, and that weak orange luminescence (600 nm) is observed after annealing at low temperatures of 500 deg C and 800 deg C. The luminescence around 600 nm becomes very intense when a thin SiO_2 sample is implanted at a substrate temperature of 400 deg C with an energy of 30 keV and a low dose of 5 X 10~15 cm~-2. It vanishes after annealing at 800 deg C for 30 min. We conclude that this luminescence observed around 600 nm is caused by some radiative defects formed in Si-implanted SiO_2. direct c 1999 Elsevier Science B.V. All rights reserved.