Numerical Investigation Including Mobility Model for the Performances of Piezoresistive Sensors

Abstract

In this work, we present an analysis based on the study of mobility, which is a very important electrical parameter of a piezoresistor and which is directly bound to the piezoresistivity effect in the piezoresistive pressure sensor. We determine how temperature affects mobility when an electrical potential is applied. For that end, a theoretical and numerical approach based on mobility in p-type Silicon piezoresistor and a finite difference model (FDM) for self-heating has been developed. So, the evolution of mobility has been established versus time for different doping levels and with temperature rise using a numerical model combined with that of mobility. Furthermore, it has been calculated for some geometric parameters of the sensor such as membrane side length and its thickness. Also, it is computed as a function of bias voltage. It was observed that mobility is strongly affected by the temperature rise induced by the applied potential when the sensor is actuated for a prolonged time. As a consequence, there is a drift in the output response of the sensor. Finally, this work makes it possible to predict their temperature behavior due to self-heating and to improve this effect by optimizing the geometric properties of the device and by reducing the voltage source applied to the bridge.