Ultralow-threshold field emission from oriented nanostructured GaN films on Si substrate

A series of nanostructured GaN Films have been prepared on Si substrates. Field emission measurements show that the oriented nanostructured GaN film with a thickness of 40 nm has an ultralow threshold field of 1.2 V/μm at 1 mA/cm2 and yields a stable emission current of 40 mA/cm2 at 2.8 V/μm, which is comparable to those of carbon nanotubes. A polarization field emission enhancement mechanism with ballistic electron transport is proposed to explain the origin of this ultralow-threshold field emission phenomenon.