Modelling and Sensing Hydrogen at Lower Operating Temperatures using Nanocrystalline Tin Oxide Thin Films

摘要

Tin oxide (SnO_x) semiconductor thin film is coated on Pyrex glass (silica) substrates using the sol-gel dip-coating technique utilizing alkoxide precursor. The thin film is extensively characterized for its surface morphology, chemistry, thickness, and nanocrystallite size using different analytical techniques such as scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and high-resolution transmission electron microscopy (HRTEM). The HRTEM sample preparation is done for the first time using focused ion-beam (FIB) milling technique. Under the given processing conditions, SnOx semiconductor thin film having thickness 100-150 nm and nanocrystallite size 6-8 nm is obtained. Maximum hydrogen gas sensitivity value of 394 % is recorded at room temperature for 4 vol. % hydrogen for the undoped nanocrystalline SnO_x semiconductor thin film sensor.