Modeling of porous silicon junction field effect transistor gas sensors: Insight into NO2 interaction

In this paper a lumped parameter electrical model for porous silicon junction field effect transistor (PSJFET) gas sensors is presented and experimentally validated. The PSJFET is an integrated p-channel JFET device modified with a porous silicon layer, the latter acting as sensing element. The model is described by using an analytical closed-form expression, which quantitatively links the sensor current to the analyte concentration in the environment, and validated by using experimental data of PSJFETs exposed to both synthetic air and NO2 with concentration of 300 ppb. Best fitting of experimental data with the proposed model allows one to get quantitative information on the effect of NO2 adsorption/desorption at the PS surface on electrical PS parameters, such as its conductance and surface charge density. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3391620]