Realization of reliable GaN nanowire transistors utilizing dielectrophoretic alignment technique

Abstract

We have utilized dielectrophoretic force for assembling long (50μmto200μm) GaN nanowires for device fabrication. These catalyst-free nanowires were grown by direct reaction of NH3 and Ga, which resulted in free-standing nanowires along with GaN microplatelets. GaN nanowires were suspended in a solvent using sonication, and using dielectrophoretic forces nanowires were assembled on prepatterned substrates (SiO2 coated Si and sapphire). With fabrication sequence using batch fabrication processes such as standard photolithography, etching, and oxide deposition we were able to realize stable GaN nanowire devices. The present technique is potentially compatible with complementary metal-oxide semicondoctor technology, and integrating nanodevices with conventional Si microelectronics on the same chip can be made possible with this technique. Utilizing this technique, high mobility (230cm2V−1s−1) GaN nanowire field effect transistors with reliable electrical characteristics have been achieved. These nanowire transistors even after prolonged period of conduction exhibited no deteriorations of their electrical properties. Several key factors in the processing that affect the device yield and reliability have been identified. Simple calculations predicted the effects of nanowire geometry, dispersing solvent, and alignment frequency on the dielectrophoretic force experienced by the nanowires.