Research On Microstructure And Properties Of Doped Silicon Thin Films Prepared By APCVD

The basic principles, features and applications of Chemical Vapor Deposition (CVD) have been discussed. And the developments and approaches of the uniform, the adhesion, and the preparation method of films deposited on the glass substrate were reviewed. The characterization methods of structure and properties of silicon films have been summarized briefly.Silicon films have been prepared by Atmosphere Pressure Chemical Vapor Deposition (APCVD) on the floating glass substrates with a gas mixture of SiH₄ and PH3 or SiH₄ and C₂H₄. The microstructure of silicon films prepared at the various deposition temperatures and mol ratio of doped gas were investigated by Fourier Transformed Infrared spectrum (FTIR), Raman scattering spectum, High- resolution electron microscope(HRTEM) and Atomic Force microscope(AFM).The effect of the deposition temperature on the structure and proerties of the silicon films were investigated in the range from 580℃ to 660℃. The results show the crystallinity of silicon film and the average grain become better with increasing of the deposition temperature, while the shifting of Si-Si-Si bond angle and the roughness, Ra descreased. The doping of the PH₃ improves the silicon crystallinity and the uniform of films.The transmissivity and the reflectance of films of various deposition temperature, ratio of PH₃ and C₂H₄ have been measured. The optical gap of films deposited with doping the C₂H₄ increased with the increasing of the ratio of C₂H₄ firstly and after reaching the max it decreased.The adhesion was measured by the scratch method. The adhesion of the films doped the C₂H₄ decreased with the increasing the ratio of C₂H₄. In the opposite way the doping of PH₃ increase the adhesion between the deposited silicon films and the glass substrate.