Characterization of Nanocrystalline Silicon Thin Films from Plasma-Enhanced Chemical Vapor Deposition

Nanocrystalline silicon (nc-Si) thin films were prepared on one inch square glass and silicon substrates. The films were deposited using plasma enhanced chemical vapor deposition (PECVD) with silane diluted to 1% in hydrogen gas. Deposited thicknesses of silicon range from 20 nm to 117 nm. The nc-Si needs to have the right ratio of hydrogen incorporated in its surface to allow good electrical conduction. These thin films are the foundation for multiple electronic components, such as conductive bridge resistive memories – memristors, and thin-film transistors (TFTs) that will be implemented into artificial neural networks and interfaces. Several different types of characterization instruments are utilized to analyze properties of the material including crystallinity that would greatly decrease the rate of material degradation. A high purity in the nanocrystalline structure better allows the thin-film transistors to be ambipolar and this purity was confirmed. Grazing incidence angle x-ray diffraction (GIXRD) and transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR) are then used to analyze the crystallite size, distribution, and percentage amorphous. Raman spectroscopy is used to analyze hydrogen mass percent.