Integrated Nanorods and Heterostructure Field Effect Transistors for Gas Sensing

We demonstrate a gas sensor that integrates an array of ZnO nanorods and AlGaN/GaN heterostructure field effect transistors (HFETs). The ZnO array, serving as a sensing probe, is selectively grown in the gate areas of the HFET. The designed structure combines the large surface-to-volume ratio of the nanostructures and unique properties of the HFET, which provide high signal amplification and thus ease in processing the signals induced by small changes in gas concentration. The fabricated structures are shown to detect hydrogen in a nitrogen background. The designed ZnO gate/AlGaN/GaN HEMT sensors operate in a broad range of temperatures and have potential use in biosensing applications.