ZnO-based Field-effect Transistors Research Articles

Laterally grown show better performance: ZnO nanorods network based field effect transistors

In this work, ZnO based field effect transistors have been demonstrated using self-aligned nanorods (NRs) network synthesized through a facile hydrothermal route. To control the alignment and orientation of nanorods two additives viz. Potassium Permanganate (KMnO4) and Potassium Dichromate (K2Cr2O7) were added into the precursor solution. The effect of additive was studied through structural and optical characterization of nanorods. Further, these nanorods were used as an active layer in field effect transistors (FETs) and the estimated field effect mobility and current on/off ratio of the devices were 0.56 × 10−4 cm2/V s and 10 for vertically aligned and 9.04 cm2/V s and 6 × 103 for laterally aligned NRs network respectively. It was observed that the transport properties of charges are associated with the alignment, size, interface junctions of NRs/NRs or NRs/electrode and trap defects/states on the surface. The possible mechanism of charge transport in network path has been systematically discussed.

Vertically Integrated Logic Circuits Constructed Using ZnO-Nanowire-Based Field-Effect Transistors on Plastic Substrates

ZnO-nanowire-based logic circuits were constructed by the vertical integration of multilayered field-effect transistors (FETs) on plastic substrates. ZnO nanowires with an average diameter of -100 nm were synthesized by thermal chemical vapor deposition for use as the channel material in FETs. The ZnO-based FETs exhibited a high I(ON)/I(OFF) of > 10(6), with the characteristic of n-type depletion modes. For vertically integrated logic circuits, three multilayer FETs were sequentially prepared. The stacked FETs were connected in series via electrodes, and C-PVPs were used for the layer-isolation material. The NOT and NAND gates exhibited large logic-swing values of -93%. These results demonstrate the feasibility of three dimensional flexible logic circuits.

High-throughput synthesis and characterization of Mg 1− xCa xO films as a lattice and valence-matched gate dielectric for ZnO based field effect transistors

Using composition-spread technique, we have grown metastable Mg 1− x Ca x O solid solution films on ZnO layers by pulsed laser deposition. All the films exhibited (1 1 1) oriented cubic phase. Despite a large miscibility gap, no phase separation took place at growth temperatures up to 700 °C, whereas an optimal growth temperature was found at 400 °C in terms of the crystallinity. The composition-spread films were characterized by X-ray diffraction mapping technique. Both lattice parameters and diffraction intensity increased with increasing the CaO composition. The present isovalent heterointerfaces realized the perfect lattice-matching by properly adjusting the CaO composition, leading to particular interest for ZnO based field effect transistors.