A study of sulfurizing SiO2 surfaces for the growth of Si/SiO2/Si structures was done in the present work. The silicon film was deposited at 250 °C by plasma enhanced chemical vapor deposition. All of the deposited Si films with or without sulfur treatment were of amorphous phases with a H2/(SiH4+H2) flow ratio less than 92%. For those films deposited at the H2/(SiH4+H2) flow ratio of 92%, a transition amorphous Si layer appeared between the SiO2 and polycrystalline silicon films in those samples without sulfur treatment. No transition amorphous Si layer was present in the sample deposited with sulfur treatment, and the largest grain size of polycrystalline silicon was estimated to be around 500 Å. The polycrystalline phase was obtained in all the silicon films deposited on SiO2/Si substrate with a H2/(SiH4+H2) flow ratio larger than 92%. This technique would be applicable towards thin film transistor fabrication.
The microstructures of low-temperature polycrystalline silicon grown both on SiO2 and Corning 7059 glass substrate are presented. The silicon was deposited by the hydrogen dilution method using electron-cyclotron-resonance chemical-vapor deposition at 250 °C without any thermal annealing. The hydrogen dilution ratios were varied from 90% to 99%. Transmission electron microscopy images, Raman shift spectra, and x-ray-diffraction (XRD) patterns of the films were obtained. The maximum grain size was about 1 μm and the crystalline fraction which was characterized from Raman shift spectra was near 100%. From the XRD patterns 〈111〉- and 〈110〉-oriented crystalline silicon grains were clearly present in the polycrystalline silicon films.
Microcrystalline silicon films were deposited by diluted-hydrogen method and hydrogen-atom-treatment method at 250°C in a plasma enhanced chemical vapor deposition system and they were characterized by nuclear magnetic resonance, Raman spectroscopy, and optical bandgap Measurements. One-Mask a-Si:H thin film transistors (TFT's) were fabricated with those microcrystalline materials as the channel layer. The highest electron mobilities of the TFT's fabricated by diluted-hydrogen method and hydrogen-atom-treatment method were 1.23 and 1.04 cm2/V•s, respectively without any thermal treatment steps.
The polycrystalline silicon films were deposited by electron cyclotron resonance chemical vapor deposition (ECR-CVD) with hydrogen dilution at 250°C and without any thermal annealing. The surface morphology and the microstructure of the poly-Si films are investigated by atomic force microscopy (AFM), plan-view transmission electron microscopy (TEM), crosssectional TEM and high resolution TEM (HRTEM). The low temperature poly-Si films deposited by ECR-CVD show a special leaf-like grain shape (plan-view) and an upside-down cone shape (3-dimensional view). The grains in the poly-Si films have preferred orientation of <112> and the longer side of the leaf-like grain is direction and the shorter side is direction. Lattice bending and interruption are found in the films. The arrangement of the atoms on the grains are well ordered, while atoms in the interfacial regions are randomly distributed. A simple grain formation model based on growth rate differences between different planes and etching effect can explain the film growth mechanism and the formation of the special grain geometry.
We have made studies on the TRANSVERSE transport properties of the porous Si made from a novel P/N junction structure. The structures of porous Si were examined for various electrochemical etching conditions and they were correlated with the electrical data. The junciton was fabricated by shallow diffusion, with porous Si formed perpendicular to the junction and between two indium ohmic contacts. This structure confines currents to the direction parallel to the surface. Distinct feature on I–V curves have been observed, including sudden rise of currents and the existence of negative differential resistances (NDR). The characteristics appeared stable and depended on the polarity of bias. Suggestions are made that the porous Si could be composed of microcrystals, and feasibility of carrier transport through quantum boxes responsible for the electrical behaviors are discussed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.