Improvement of the electrical properties of nanocrystalline silicon films by the KrF pulsed excimer laser irradiation method

The effects of laser fluence on the microstructure and electrical properties of nanocrystalline silicon films were investigated on samples prepared by a plasma-enhanced chemical vapor deposition technique. It was found that the content of hydrogen in the films could be reduced gradually by increasing the laser fluence, accompanied by the formation of nc-Si. The evolution of hydrogen is responsible for a change in the optical band gap and dark conductivity. By controlling the laser fluence at 1.0 J cm(-2), a dark conductivity as high as 5.9 x 10(-3) S cm(-1) could be obtained. Based on measurements of the temperature-dependent conductivity, the carrier transport processes are discussed. The effusion of hydrogen and the increase of crystallinity are thought to be contributed to the high dark conductivity and low conductivity activation energy.