Highly sensitive and stable H2 gas sensor based on p-PdO-n-WO3-heterostructure-homogeneously-dispersing thin film

Abstract

The film-based gas sensor owning high compatibility with semiconductor device fabrication, plays an important role in the miniaturization and integration of the devices. Here, simple metal organic decomposition method and calcining procedure were used to prepare dense WO3 thin film with PdO nanoparticles being homogeneously dispersed. After painting the silver paste on its surface as electrodes, the H2 gas sensor was fabricated. At the optimal operating temperature of 160 °C, with response values (Ra/Rg) of 1.2 & 45.1 and response time of 38 s & 4 s, towards 500 ppb and 100 ppm H2, respectively, the sensor presents high sensitivity and low detection limit together. It is rare to report the H2 gas sensor based on dense semiconductor film with such low detection limit. Towards 500 ppb and 100 ppm H2, it still shows the same response values more than half a year later, which proves its stability. A good linear behaviour between the response and relative humidity is observed too. The chief cause of the better performance of the sensor may be the homogeneous and optimal distribution of the p-type PdO nanoparticles in n-type WO3 film, which is the character of this structure. In addition, the repeatability of the preparing process is very well too. All the better performances suggest that the H2 sensor based on this structure has a huge potential in practical application.