Physical Study by Surface Characterizations of Sarin Sensor on the Basis of Chemically Functionalized Silicon Nanoribbon Field Effect Transistor

Surface characterizations of an organophosphorus (OP) gas detector based on chemically functionalized silicon nanoribbon field-effect transistor (SiNR-FET) were performed by Kelvin probe force microscopy (KPFM) and time-of-flight secondary-ion mass spectrometry (ToF-SIMS) and were correlated with changes in the current–voltage characteristics of the devices. KPFM measurements on FETs allow us (1) to investigate the contact potential difference (CPD) distribution of the polarized device as a function of the gate voltage and the exposure to OP traces and (2) to analyze the CPD hysteresis associated with the presence of mobile ions on the surface. The CPD measured by KPFM on the silicon nanoribbon was corrected because of side capacitance effects in order to determine the real quantitative surface potential. Comparison with macroscopic Kelvin probe (KP) experiments on larger surfaces was carried out. These two approaches were quantitatively consistent. An important increase of the CPD values (between +399 mV...