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

Abstract

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.

Influence of current-induced recrystallization on piezoresistive properties of polysilicon nanosized thin films deposited at different temperatures

“…Our previous research work [1,2] indicates that polysilicon nanosized thin films (PNTFs, ~80nm in thickness) exhibit larger gauge factor (GF ≥ 34) and better temperature stability than polysilicon thick films (> 200nm in thickness, GF is 20~25) at high doping level. It makes PNTFs potential for the fabrication and application of piezoresistive sensors with low temperature drift and high sensitivity.…”

Piezoresistive Sensitivity, Linearity and Resistance Time Drift of Polysilicon Nanofilms with Different Deposition Temperatures

“…However, our previous experimental results indicated that boron-doped PSNFs exhibit higher piezoresistive sensitivity (GF ≥ 30) at high doping concentrations than PSCFs (GF is only 20∼25) at the same doping levels [ 20 , 21 ]. Interestingly, as the doping level exceeds 2×10 20 cm -3 , the GF of PSNFs increases with elevating doping concentration [ 22 ].…”

“…These unique physical properties of heavily doped PSNFs make the material potential for the development of low cost, high temperature stability and miniature volume piezoresistive sensors. Consequently, in order to analyze the piezoresistive properties of highly doped PSNFs, the tunneling effect was introduced and considered as the dominant transport mechanism of carriers traversing GBs in our previous work [ 20 , 22 ]. The theoretical prediction of GF versus doping concentration gives better agreement with the experimental data than the existing models [ 21 ].…”