The influences of thickness on piezoresistive properties of poly-Si nanofilms

摘要

Experiments show that the gauge factor of poly-Si film is biggish when its thickness is in the range of nano scale, which cannot be explained reasonably by existing piezoresistive theories. This paper focuses on how gauge factor varies with film thickness, analyzes the origin of poly-Si piezoresistive properties under the circumstance of small grain size, and indicates that tunneling current going through grain boundary barrier is influenced by the strain, which makes the enhancement of piezoresistive effect at gain boundary. Based on these, a modified model on poly-Si piezoresistive properties is proposed, and it fits the experimental results well.