Electron mobility in nanocrystalline silicon devices

Electron mobility in the growth direction was measured using space charge limited current techniques in device-type nin structure nanocrystalline Si:H and nanocrystalline Ge:H structures. The films were grown on stainless steel foil using either hot wire or remote plasma enhanced chemical vapor deposition techniques. Grain size and crystallinity were measured using x ray and Raman spectroscopy. The size of grains in films was adjusted by changing the deposition conditions. It was found that large ⟨220⟩ grain sizes (∼56nm) could be obtained using the hot wire deposition technique, and the conductivity mobility at room temperature was measured to be 5.4cm2∕Vs in films with such large grains. The plasma-grown films had smaller grains and smaller mobilities. The mobility was found to increase with increasing grain size and with increasing temperature.