Temperature Dependence of The Hall Mobility in Polycrystalline Silicon

Crystallization of amorphous silicon thin films by various methods has fostered enhancements in the electrical characteristics over their amorphous counterparts. For example, carrier mobilities ranging from 10 to >100 cm2/V·sec have been reported for laser crystallized films. The rather large variability of the transport characteristics with crystallization processing conditions is not well understood and, as a result, greatly complicates device process debugging. In addition, while it is generally believed that defects inherent in the grain boundaries provide the primary barriers degrading transport properties relative to single crystal silicon, the specific nature of these defects is not known. In this paper, we present data on the temperature dependence of the Hall mobility of thin silicon films crystallized by thermal and excimer laser processing. Hall data for the laser-crystallized phosphorus-doped material show a temperature dependence which differs dramatically from that for thermally crystallized materials, while the effects of hydrogenation are similar, reducing the barriers at the grain boundaries.REFERENCES