High hydrogen response of Pd/TiO2/SiO2/Si multilayers at room temperature

• Pd/TiO2/SiO2/Si multilayers were produced using magnetron sputtering method.
• The multilayers show a high response (∼2431%) to 1% H2 in air.
• The gas sensing mechanism of Pd/TiO2/SiO2/Si multilayers is proposed.

A series of Pd/TiO2/SiO2/Si multilayers were produced using magnetron sputtering method. It is found that H2 molecules have dramatic effect on the current–voltage (I–V) characteristics of the Pd/TiO2/SiO2/Si multilayers at room temperature (RT). When Pd/TiO2/SiO2/Si multilayer is exposed to H2, the Pd film quickly reacts with H2 and forms palladium hydride which results in transferring more electrons from the Pd film to TiO2 film. Therefore, the I–V characteristic of Pd/TiO2/SiO2/Si multilayer was greatly changed when exposed to H2. For example, a Pd/TiO2/SiO2/p-Si multilayer can show a high response (∼2431%) to 1% H2 with appreciable short response time of 13 s and recovery time of 4 s at RT. Besides, it is demonstrated that Si substrate has a great effect on the H2 response of Pd/TiO2/SiO2/Si multilayers. When exposed to H2 the current of Pd/TiO2/SiO2/p-Si multilayer at −0.5 V greatly decreases while the current of Pd/TiO2/SiO2/n-Si multilayer greatly increase, which can be understood by their energy band structures.

The Pd/TiO2/SiO2/p-Si multilayer shows a high response (∼2431%) to H2with appreciable short response time of 13 s and recovery time of 4 s at room temperature.Figure optionsDownload as PowerPoint slide