Microstructure and carrier-transport behaviors of nanocrystalline silicon thin films annealed at various temperatures.

Hydrogenated amorphous Si films were prepared by a plasma-enhanced chemical vapor deposition technique. As-deposited samples were then thermally annealed at various temperatures to obtain nanocrystalline silicon films. The microstructures and carrier-transport characteristics were investigated during the transition process from amorphous to nanocrystalline phase. It was found that the Hall mobility was improved while the dark conductivity was increased by over two orders of magnitude after annealing. Temperature-dependent Hall measurements were performed in the temperature range from 310 to 575 K. Hall mobility first increases with rising temperature to 400 K and then decreases with further increasing temperature. The different temperature dependence of Hall mobility shows that the microscopic mechanisms governing charge transport are different for nanocrystalline Si films in different temperature regions. [ABSTRACT FROM AUTHOR]