We report low-hysteresis, ambipolar bottom
gold contact, colloidal
PbSe nanowire (NW) field-effect transistors (
FETs) by chemically modifying the
silicon dioxide (SiO(2)) gate dielectric surface to overcome carrier trapping at the NW-gate dielectric interface. While water bound to
silanol groups at the SiO(2) surface are believed to give rise to hysteresis in
FETs of a wide range of nanoscale materials, we show that
dehydration and silanization are insufficient in reducing
PbSe NW FET hysteresis. Encapsulating
PbSe NW
FETs in cured
poly(methyl) methacrylate (
PMMA), dehydrates and uniquely passivates the SiO(2) surface, to form low-hysteresis
FETs. Annealing predominantly p-type ambipolar
PbSe NW
FETs switches the FET behavior to predominantly n-type ambipolar, both with and without
PMMA passivation. Heating the
PbSe NW devices desorbs surface bound
oxygen, even present in the atmosphere of an inert glovebox. Upon cooling, overtime
oxygen readsorption switches the FET polarity to predominantly p-type ambipolar behavior, but
PMMA encapsulation maintains low hysteresis. Unfortunately
PMMA is sensitive to most
solvents and heat treatments and therefore its application for nanostructured material deposition and doping is limited. Seeking a robust, general platform for low-hysteresis
FETs we explored a variety of
hydroxyl-free substrate surfaces, including
silicon nitride, polyimide, and
parylene, which show reduced electron trapping, but still large hysteresis. We identified a robust dielectric stack by assembling octadecylphosphonic
acid (ODPA) on
aluminum oxide (Al(2)O(3)) to form low-hysteresis
FETs. We further integrated the ODPA/Al(2)O(3) gate dielectric stack on flexible substrates to demonstrate low-hysteresis, low-voltage
FETs, and the promise of these nanostructured materials in flexible, electronic circuitry.