Enhancement of electron mobility in nanocrystalline silicon crystalline silicon heterostructures

We report on an effective way to obtain high electron mobility (similar to10(3) cm(2)/V s) in lowly doped hydrogenated nanocrystalline silicon (nc-Si:H) thin films by constructing nc-Si:H/crystalline Si (c-Si) heterostructures. The enhancement has been demonstrated in a comparative study on nc-Si:H thin films grown on p- and n-type c-Si, as well as insulating glass substrates through temperature- and magnetic-field-dependent Hall-effect measurements. The effect has been attributed to the ordered structure and narrow boundaries between the nanograins, with the help of microstructure pictures from high-resolution transmission electron microscopy. In addition to the detailed individual transport information of carriers in the nc-Si:H systems, we observe clear evidence for the formation of a two-dimensional electron gas at the nc-Si:H/c-Si interfaces. These results are discussed within the framework of the Boltzmann theory and the quantum interference theory. (C) 2005 American Institute of Physics.