We present silicon-compatible trigated p-Ge/i-Si/n-Si axial heteronanowire tunneling field-effect transistors (TFETs), where on-state tunneling occurs in the Ge drain section, while off-state leakage is dominated by the Si junction in the source. Our TFETs have high I(ON) ~ 2 μA/μm, fully suppressed ambipolarity, and a subthreshold slope SS ~ 140 mV/decade over 4 decades of current with lowest SS ~ 50 mV/decade. Device operation in the tunneling mode is confirmed by three-dimensional TCAD simulation. Interestingly, in addition to the TFET mode, our devices work as standard nanowire FETs with a good I(ON)/I(OFF) ratio when the source-drain junction is forward-biased. The improved transport in both biasing modes confirms the benefits of utilizing bandgap engineered axial nanowires for enhancing device performance.

Physical-gap-channel graphene field effect transistor with high on/off current ratio for digital logic applications Appl. Phys. Lett. 101, 143102 (2012) Short channel mobility analysis of SiGe nanowire p-type field effect transistors: Origins of the strain induced performance improvement Appl. Phys. Lett. 101, 143502 (2012) Terahetz detection by heterostructed InAs/InSb nanowire based field effect transistors Development of high-performance fully depleted silicon-on-insulator based extended-gate field-effect transistor using the parasitic bipolar junction transistor effect Appl. Phys. Lett. 101, 133703 (2012) Abnormal interface state generation under positive bias stress in TiN/HfO2 p-channel metal-oxide-semiconductor field effect transistors

We report on vapor-liquid-solid growth and electrical properties of axial in situ doped p-n junction Ge sub-100 nm diameter nanowires. Room temperature four-point measurements show current rectification of two to three orders of magnitude depending on nanowire doping and diameter. We observe strong backgate control of reverse-bias current of up to three orders of magnitude and explain it by band-to-band tunneling modulated by the backgate-controlled electric field, as confirmed qualitatively via a quasi-three-dimensional Schrödinger-Poisson simulation.