Microstructure and conductivity of large area nanocrystalline silicon films grown by specially designed thermal-assisted chemical vapor deposition

Large-area thin films of silicon consisting of an amorphous matrix with embedded silicon nanocrystallites were deposited on glass substrates using a specially-designed thermal-assisted chemical vapor deposition technique that is compatible with the mature silicon technology. Under this way, the typical nanocrystalline silicon film was grown at 660 degreesC with crystallization ratio of over 50% and average silicon crystallite size approximately 8-12 nm. The deposition temperature and the post-annealing procedure determine the nanocrystalline Si fraction in the amorphous matrix, which affects the room-temperature dark conductivity of the film. The thermal-assisted tunneling of carriers between neighboring silicon nanocrystallites embedded in amorphous matrix was suggested, which coincides with the theory of hetero-quantum dots. (C) 2002 Elsevier Science B.V. All rights reserved.