NEWS
Dynamic control over electronic transport is shown in ultra-high surface area graphene based bulk materials. The large macroscopic conductance of the nanographene monoliths can be varied up to several hundred percent with electrolyte-gating; paving ways towards carbon based bulk transistors.
Advanced Materials 2012 Electrolyte-gated high speed nanowire electronicsMax. attainable speed of electrolyte-gating is tested with ideal transistor channel made of single crystalline oxide nanowires to conclude low voltage driven and long-term stable FETs are viable that show excellent electrical performance and potential to work with MHz switching frequencies.
Solution-processed oxide semiconductors are often criticized for their processing related issues, especially high temperature requirements. However, we have demonstrated that easily printable oxide nanoparticulate based inks can lead to field-effect transistor devices that are completely processed at room temperature.
ry rough printed (nanoparticulate) semiconductor layers towards high gating efficiency and excellent electrical performance.
Figure 1 Processing temperature versus field-effect mobility of the inorganic oxide semiconductor channel FETs from the literature to compare with our room temperature processed devices.
Composite solid polymer electrolytes (CSPE) are combination of a synthetic polymer, a solvent, a plasticizer and a salt. The novel CSPE developed in the printable electronics group at INT simultaneously easily printable (with fluid dynamic properties ideally suitable for ink-jet), highly transparent, shows high polarizability, extremely low leakage within small potential ranges i.e. essentially used and long-term performance stability in air.
Figure 2 UV-Vis spectroscopy and an optical image (inset) of a 150 µm thick composite solid polymer electrolyte membrane showing high transparency in the visible wavelengths.
Figure 3 Cyclic voltammetry measurements showing the long-term stability of polarizability of the composite solid polymer electrolyte in air. The circle and square symbols indicate the current density and the specific charge density on the electrodes, respectively.
Consequently, the transistors made from the unique CSPE also show performance stability when left in air ambiance.
Figure 4 Transfer characteristics of an individual electrolyte-gated nanowire channel transistor device measured with respect to aging time in air.
Semiconducting oxide nanowires are grown via either a vapor-liquid-solid (VLS) growth method or using solvothermal synthesis method.
Figure 5 Structural and morphological characterization of nanowires with electron microscopy. Scanning and transmission electron microscopy image of VLS-mode grown ZnO (left) and SnO2 (right) nanowires.
Figure 6 Transfer curve of SnO2 nanowire channel, n-type MOSFET (NMOS) (left) and Cu2O nanowire channel, p-type MOSFET (PMOS) device (right).We are able to demonstrate electrolyte-gated nanowire FETs with switching speed >100 kHz, even for an in-plane device geometry.
Figure 7 Time-transient measurement showing the switching speed of a single zinc oxide nanowire electrolyte-gated FET device; a) the gate voltage VG is pulsed, b) the corresponding drain current (ID) response is recorded, the rise and fall segments of the drain currents are separately fitted with exponential decay equations in order to obtain switching speed in excess of 100 kHz.
