Low temperature low ppm acetone detection by Pd/TiO2/p-Si Metal-Insulator-Semiconductor devices

In this present investigation nanocrystalline TiO₂ based sensor was developed for low ppm level (10-100) acetone detection. TiO₂ thin film (Thickness: 1 μm) was prepared by solgel technique and deposited on the p-Si substrate (5 Ωcm, (100)) by dip coating method. Film was annealed at 450°C for 3 hours in air environment. XRD and FESEM study confirmed the (101) anatase growth with ~6-9 nm particle size. Pd electrode was deposited on the TiO₂ sensing layer to prepare the Pd/TiO₂/p-Si Metal-Insulator-Semiconductor (MIS) device structure. A detailed acetone sensor study was performed for this MIS device in the temperature range of 100 to 200°C. Sensor showed a repeatable sensing performance with a appreciably fast response time of 7.7 s at 100°C towards 10 ppm acetone with corresponding recovery time of 13 s at 200°C in 10 ppm acetone. Response magnitude was increased from 3.2% to 6.4% with increasing the acetone concentration from 10 to 100 ppm at 200°C.