Muhammad Hussain1, Woonyoung Jeong1, Il-Suk Kang2, Kyeong-Keun Choi3, Syed Hassan Abbas Jaffery1, Asif Ali1, Tassawar Hussain1, Muhammad Ayaz4, Sajjad Hussain1, Jongwan Jung1. 1. Department of Nanotechnology and Advanced Materials Engineering and HMC, Sejong University, Seoul 05006, Korea. 2. National Nanofab Center, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Korea. 3. NINT (National Institute for Nanomaterials Technology), Pohang University of Science and Technology, Pohang 37673, Korea. 4. Department of Electronic Engineering, Semyung University, Chungcheongbuk-do 27136, Korea.
Abstract
Herein, the fabrication of a novel highly sensitive and fast hydrogen (H2) gas sensor, based on the Ta2O5 Schottky diode, is described. First, Ta2O5 thin films are deposited on silicon carbide (SiC) and silicon (Si) substrates via a radio frequency (RF) sputtering method. Then, Pd and Ni are respectively deposited on the front and back of the device. The deposited Pd serves as a H2 catalyst, while the Ni functions as an Ohmic contact. The devices are then tested under various concentrations of H2 gas at operating temperatures of 300, 500, and 700 °C. The results indicate that the Pd/Ta2O5 Schottky diode on the SiC substrate exhibits larger concentration and temperature sensitivities than those of the device based on the Si substrate. In addition, the optimum operating temperature of the Pd/Ta2O5 Schottky diode for use in H2 sensing is shown to be about 300 °C. At this optimum temperature, the dynamic responses of the sensors towards various concentrations of H2 gas are then examined under a constant bias current of 1 mA. The results indicate a fast rise time of 7.1 s, and a decay of 18 s, for the sensor based on the SiC substrate.
Herein, the fabrication of a novel highly sensitive and fast n class="Chemical">pan class="Chemical">hydrogen (H2) class="Chemical">n>n class="Gene">gas sensor, based on the Ta2O5Schottky diode, is described. First, Ta2O5 thin films are deposited on silicon carbide (SiC) and silicon (Si) substrates via a radio frequency (RF) sputtering method. Then, Pd and Ni are respectively deposited on the front and back of the device. The deposited Pd serves as a H2 catalyst, while the Ni functions as an Ohmic contact. The devices are then tested under various concentrations of H2 gas at operating temperatures of 300, 500, and 700 °C. The results indicate that the Pd/Ta2O5Schottky diode on the SiC substrate exhibits larger concentration and temperature sensitivities than those of the device based on the Si substrate. In addition, the optimum operating temperature of the Pd/Ta2O5Schottky diode for use in H2 sensing is shown to be about 300 °C. At this optimum temperature, the dynamic responses of the sensors towards various concentrations of H2 gas are then examined under a constant bias current of 1 mA. The results indicate a fast rise time of 7.1 s, and a decay of 18 s, for the sensor based on the SiC substrate.
Authors: Jesse D Fowler; Matthew J Allen; Vincent C Tung; Yang Yang; Richard B Kaner; Bruce H Weiller Journal: ACS Nano Date: 2009-02-24 Impact factor: 15.881