Silicon nanocrystal formation in silicon-rich silicon oxide thin films

Abstract

Silicon rich silicon oxide thin films have been fabricated by electron cyclotron resonance plasma enhanced chemical vapor deposition. Following their deposition, these films were subjected to thermal anneals at temperatures up to 1100°C for times of up to 120 minutes. Annealing of the films causes a phase separation of the material to form Si precipitates, which nucleate to form Si nanocrystals, within an amorphous SiO 2 matrix. The nucleation of the nanocrystals was analyzed as a function of the composition of the films, as determined by Rutherford backscattering and elastic recoil detection analysis experiments, and the annealing conditions. The bonding structure of the films was analyzed using Fourier transform infrared spectroscopy. Surface morphology, including analysis of the size and distribution of the nanocrystals, was determined through the use of atomic force microscopy. Spectroscopic ellipsometry, in the range from 600 to 1100 nm, was used to examine the effects of the formation of nanocrystals on the optical properties, i.e., index of refraction and extinction coefficient, of the films. Photoluminescence spectra were used to show that due to quantum confinement effects the nanocrystals exhibit luminescence, making them a potential candidate for integrated photonic emitters.