Simple planar structure hydrogen gas sensor device with large response

Hydrogen gas sensor device with simple planar structure based on p(+) silicon substrate with n-type epi-layer was fabricated only by using a lift-off technique of an evaporated metal film. The device consists of Ohmic source and drain electrodes and platinum Schottky gate electrode. This sensor device has a little similar property as FET. Current-voltage characteristics between the source and drain of the device are sensitive to hydrogen gas. The voltage difference between in hydrogen ambient and oxygen ambient is about 2.3 volts for a constant current of 0.9 mA. The device can detect 0.4% hydrogen gas in air. Based on oxidation reaction of hydrogen on the surface of the platinum gate, hydrogen sensitivity of the device changes by the coexisting oxygen concentration. Electrons flow in the buried channel formed between the gate electrode and the p(+)n junction. It was confirmed that the gate bias influences the properties. The current-voltage property changes also depending on the wiring method.