Nanocrystalline p-TiO2 based MIS device for efficient acetone detection

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.