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Piezoresistive Sensitivity, Linearity and Resistance Time Drift of Polysilicon Nanofilms with Different Deposition Temperatures
MEMS Center, Harbin Institute of Technology, Harbin 150001, Heilongjiang Province, P.R. China
Key Laboratory of Micro-Systems and Micro-Structures Manufacturing, Ministry of Education, P.R. China
Information Science and Engineering School, Shenyang University of Technology, Shenyang, Liaoning Province, P.R. China
* Author to whom correspondence should be addressed.
Received: 23 January 2009; in revised form: 12 February 2009 / Accepted: 18 February 2009 / Published: 23 February 2009
Abstract: Our previous research work indicated that highly boron doped polysilicon nanofilms (≤100 nm in thickness) have higher gauge factor (the maximum is ~34 for 80 nm-thick films) and better temperature stability than common polysilicon films (≥ 200nm in thickness) at the same doping levels. Therefore, in order to further analyze the influence of deposition temperature on the film structure and piezoresistance performance, the piezoresistive sensitivity, piezoresistive linearity (PRL) and resistance time drift (RTD) of 80 nm-thick highly boron doped polysilicon nanofilms (PSNFs) with different deposition temperatures were studied here. The tunneling piezoresistive model was established to explain the relationship between the measured gauge factors (GFs) and deposition temperature. It was seen that the piezoresistance coefficient (PRC) of composite grain boundaries is higher than that of grains and the magnitude of GF is dependent on the resistivity of grain boundary (GB) barriers and the weight of the resistivity of composite GBs in the film resistivity. In the investigations on PRL and RTD, the interstitial-vacancy (IV) model was established to model GBs as the accumulation of IV pairs. And the recrystallization of metastable IV pairs caused by material deformation or current excitation is considered as the prime reason for piezoresistive nonlinearity (PRNL) and RTD. Finally, the optimal deposition temperature for the improvement of film performance and reliability is about 620 °C and the high temperature annealing is not very effective in improving the piezoresistive performance of PSNFs deposited at lower temperatures.
Keywords: Polysilicon nanofilm; Piezoresistive effect; Linearity; Resistance time drift; Tunneling; Interstitial-vacancy pair; Deposition temperature
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MDPI and ACS Style
Shi, C.; Liu, X.; Chuai, R. Piezoresistive Sensitivity, Linearity and Resistance Time Drift of Polysilicon Nanofilms with Different Deposition Temperatures. Sensors 2009, 9, 1141-1166.
Shi C, Liu X, Chuai R. Piezoresistive Sensitivity, Linearity and Resistance Time Drift of Polysilicon Nanofilms with Different Deposition Temperatures. Sensors. 2009; 9(2):1141-1166.
Shi, Changzhi; Liu, Xiaowei; Chuai, Rongyan. 2009. "Piezoresistive Sensitivity, Linearity and Resistance Time Drift of Polysilicon Nanofilms with Different Deposition Temperatures." Sensors 9, no. 2: 1141-1166.