Keywords: nanocrystalline silicon, photoluminescence, grain size, plasma CVD, chemical vapour deposition, deposition temperature, air exposure time, nanomaterials, nanotechnology, luminescence properties
Improved luminescence properties of nanocrystalline silicon films deposited by plasma enhanced chemical vapour deposition technique at low temperature
Nanocrystalline silicon (nc-Si) films have been prepared by plasma-enhanced chemical vapour deposition (PECVD). The feed gases were SiF4/SiH4/H2. The deposition temperature, Td and the air exposure time were varied. The optical properties of the films were evaluated by measurement of the photoluminescence (PL) and the structural properties were investigated by measurements of x-ray diffraction, Fourier transform infrared absorption and Raman scattering. The structural changed from an amorphous to a nanocrystalline phase at Td = 80°C. In addition, it suggests that Td low condition lead to the increase in the density of SiH-related bonds and a decrease in the average grain size, <δ>. The oxygen absorption peak increases with the air exposure time. The PL intensity increases and blue shifts consistently with the decrease of <δ> and increase of oxygen content.