Electrical properties dependent on H2 gas for new structure diode of Pt-thin WO3-SiC

A normal Schottky diode based on a catalytic metal-semiconductor structure exhibits a response to hydrogen of 1 V at most. In order to improve the response, a diode based on silicon carbide and of Pt-thin WO3-SiC structure was fabricated. The current-voltage (I-V) and capacitance-voltage (C-V) characteristics were measured in H-2 and O-2 atmospheres within a temperature range of 25-300 degreesC. The Schottky barrier height of the diode varies according to the atmosphere. In addition, the series resistance of the diode in an O-2 atmosphere increases with the thickness of WO3, and a difference in series resistance of the diode between an O-2 atmosphere and an H-2 atmosphere yields an increase in the voltage response up to 3 V, depending on the forward current. The slope of a 1/C-2-Vplot of the diode becomes gentle with increasing temperature in an H-2 atmosphere, and when temperature is held at 300 degreesC the slope becomes gentle with increasing H-2 concentration. The effective area of the electrode, which is evaluated from the slope, depends on hydrogen concentration of the atmosphere. A change of the effective area is originated on Langmuir-type adsorption of hydrogen. Current spreading effect in WO3 layer is discussed. (C) 2003 Elsevier B.V. All rights reserved.