Multiple contacts investigation of single silicon nanowires with the active voltage contrast scanning electron microscopy technique

摘要

A method for analysing the formation of electrical contacts to single silicon nanowires (Si NWs) by exploiting scanning electron microscopy (SEM) images, using active secondary electrons voltage contrast, is presented. Our approach clearly demonstrates the advantages of the proposed technique in analysing multiple contacts to a single nanowire simultaneously, in comparison to the conventional voltage contrast technique, where only two contact structures can be analysed, mainly for studies of the material dopant's profile. The SEM is equipped with an in-lens detector, which collects the secondary electrons generated during electron beam exposure of the sample. Biasing the contacts with different voltages has been used to analyse the metal to Si NW contacts. The secondary electrons are sensitive to the potential distribution and the contrast of the SEM image changes depending on the number of secondary electrons detected. The Si NWs also vary their contrast together with the electrodes if they are properly electrically contacted. The basic tools and fixtures required for such measurements, and the corresponding image processing algorithms are described.