EFFECTS OF MICROSTRUCTURE ON THE PIEZORESISTANCE OF THIN POLYSILICON LAYERS

A physical model of piezoresistance in thin polysilicon layers is deve loped taking into account the contributions of intergranular potential barriers and preferential grain orientation. The contribution of the intergranular barrier depends strongly on the average grain size L. In unrecrystallized, fine-grained poly-Si (L similar or equal to 120 nm) , the effect of potential barrier is significant over the entire range of concentrations and temperatures examined. In laser-recrystallized, large-grained poly-Si (L similar or equal to 100 mu m) at high temper atures and dopant concentrations, the contribution of the intergranula r barrier is negligible.