Electronic Transport Imaging in a Multiwire SnO2 ChemFET Device

摘要

The electronic transport and the sensing performance of an individual SnO2crossed nanowires device in a three-terminal field effect configuration wereinvestigated using a combination of macroscopic transport measurements andScanning Surface Potential Microscopy (SSPM). The structure of the device wasdetermined using both Scanning Electron- and Atomic Force Microscopy data. TheSSPM images of two crossed 1D nanostructures, simulating a prototypicalnanowire network sensors, exhibit large dc potential drops at the crossed-wirejunction and at the contacts, identifying them as the primary electroactiveelements in the circuit. The gas sensitivity of this device was comparable tothose of sensors formed by individual homogeneous nanostructures of similardimensions. Under ambient conditions, the DC transport measurements were foundto be strongly affected by field-induced surface charges on the nanostructureand the gate oxide. These charges result in a memory effect in transportmeasurements and charge dynamics which are visualized by SSPM. Finally,scanning probe microscopy is used to measure the current-voltagecharacteristics of individual active circuit elements, paving the way to adetailed understanding of chemical functionality at the level of an individualelectroactive element in an individual nanowire.