Effect of Schottky barrier height on hydrogen gas sensitivity of metal/TiO<inf>2</inf> nanoplates

Anatase phase dominated TiO2 nanoplates were deposited on p-Si by Radio-Frequency magnetron sputtering technique. Metal-TiO2 nanoplates-Metal (M-TN-M) planer electrodes were fabricated using various metal electrodes such as Al, Ag, Ni, and Au. Temperature dependent current-voltage (I-V) characteristics of M-TN-M devices were measured in air and 1% hydrogen atmosphere. Barrier height between metal and TiO2 nanoplates is decreased in presence of hydrogen as compared to air and increases with temperature. The sensing response of the device is strongly dependent on the alteration of barrier height and operating temperature. The relative response was observed ∼46% for Ohmic Al electrodes. The effective barrier heights were measured to be ∼0.15 eV for Ag, ∼0.17 eV for Ni and ∼0.19 eV for Au electrodes at 175 °C and corresponding change in relative response were measured ∼49%, ∼58%, and ∼77%, respectively. Response and recovery times for highest sensitivity device (Au-TN-Au) were found to be ∼7 and 114 s respectively at 175 °C operating temperature.