Structural and optical properties of Si∕SiO2 superlattices prepared by low pressure chemical vapor deposition

Abstract

Si ∕ Si O 2 superlattices (SLs) structures were prepared using a low-pressure chemical vapor deposition (LPCVD) method. The structural and optical properties of the SLs materials were characterized using atomic force microscopy (AFM), Fourier transformed infrared (FTIR) absorption, x-ray diffraction, and room-temperature photoluminescence (PL) measurements. The AFM results show that a periodically layered Si∕SiO2 structure was successfully deposited with nanometer-sized Si dots embedded in the Si layers. The FTIR spectra show that the SiO2 near the Si∕SiO2 interface is more ordered than the amorphous SiO2 in the center of the SiO2 layers. The Si∕SiO2 SLs films show a room-temperature PL in the visible-near infrared wavelength region. The PL intensity is significantly enhanced by a high-temperature annealing at 1100°C. The peak position and intensity of the main emission band in the PL spectra strongly depend on the Si layer thickness. A pronounced redshift with increasing Si layer thickness is observed. This emission peak position can be fitted by the theory of quantum confinement effect in Si dots. The emission from recombination through defect and interface states was also observed in the SLs films.