Highly Fast Response of Pd/Ta2O5/SiC and Pd/Ta2O5/Si Schottky Diode-Based Hydrogen Sensors

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.

Biological sensing using anomalous hall effect devices

“…Prior to functionalization, most of the oxygen signal was provided by the Ta-O bond (531.6 eV) and Ta-OH bond (533.0 eV). The 533.8 eV signal can be attributed to the adhesion of water vapor to the surface [26,27]. After TESUD functionalization, the oxygen signal came from the Ta-O-Si bond (532.2 eV) at one end of TESUD, the C=O bond (529.9 eV) at the other end of the TESUD, the Ta-O bond (531.5 eV), and the Si-O-Si bond (532.5 eV) [].…”

Review of Hydrogen Gas Sensors for Future Hydrogen Mobility Infrastructure

“…Qi et al [37] evaluated a SiC Schottky diode hydrogen sensor with a trench-insulator structure; a Pd/Ta 2 O 5 /SiC Schottky diode hydrogen sensor operating at 300 ∘ C with a SiC substrate was also reported [shown in Figs. 3(a)-(c)] [38]. Chen et al [39] developed a Schottky diode hydrogen sensor based on a Pt thin film/NP hybrid structure and GaN/AlGaN.…”

Schottky diode on Silicon Carbide (SiC): ideal detector for very wide temperature range sensors

“…The primary application areas for SiC Schottky diodes are in power factor correction circuits, power supplies, photovoltaic inverters and sensors [3][4][5][6][7][8][9][10][11][12][13][14] . The main advantage of the SBD is the practical absence of reverse recovery current during switching, hence it is possible to increase the switching frequency considerably.…”

“…Sensors are already available in SiC for high temperature operation, for instance as gas sensors. Other potential sensor types of interest are for temperature and pressure monitoring [4][5][6][7][8][9][10][11][12][13][14][15][16] . With a suitable readout circuit, more applications would open due to higher signal integrity and improved system performance.…”