Nanocrystalline p-TiO2 based MIS device for efficient acetone detection

Abstract

Present study investigated, the acetone sensing properties of Pd/TiO2/Si Metal Insulator Semiconductor (MIS) devices with nanocrystalline p-TiO2, with crystalline size ~8 nm as the sensing layer. p-TiO2 thin film was synthesized using sol-gel method. After details structural characterization by X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM) and electrical characterization by Van Der Pauw method, the MIS structure was fabricated employing drop coated p-Si substrate. Pd was deposited, on TiO2, as noble metal catalytic electrode while Al was taken as ohmic contact electrode from Si. The sensor study was carried out at relatively lower operating temperatures (50-200°C) for the acetone concentrations of 0.5-50ppm. It was found that MIS devices showed fast response/recovery with appreciable response magnitude in the entire temperature range for all the concentration. The faster response/recovery of MIS devices has been analyzed through an electrical equivalent model including the effect of barrier height between grain boundaries (GBs) and hole trapping at GBs interfaces.