Vertical InAs Nanowire Wrap Gate Transistors on Si Substrates

We report on InAs enhancement-mode field-effect transistors integrated directly on Si substrates. The transistors consist of vertical InAs nanowires, grown on Si substrates without the use of metal seed particles, and they are processed with a 50-nm-long metal wrap gate and high-$kappa$ gate dielectric. Device characteristics showing enhancement-mode operation are reported. The output characteristics are asymmetric due to the band alignment and band bending at the InAs/Si interface. The implemented transistor geometry can therefore also serve as a test structure for investigating the InAs/Si heterointerface. From temperature-dependent measurements, we deduce an activation energy of about 200 meV for the InAs/Si conduction band offset.