Oxide thin-film transistors (TFTs) were fabricated using a polycrystalline In-Ga-O (IGO) thin film as the n-channel active layer by direct current magnetron sputtering. The 50-nm-thick IGO TFT showed a field-effect mobility of 39.1 cm 2 V À1 s À1 , a threshold voltage of 1.4 V, and a subthreshold gate voltage swing of 0.12 V/decade. The polycrystalline IGO thin film showed the cubic bixbyite structure of In 2 O 3 without an obvious preferred orientation. The average grain size of polycrystalline IGO was approximately 10 m. The high mobility of IGO TFT is related to the In 2 O 3 crystalline phase and large grain size of the IGO film. #

The authors have found that pentacene molecules deposited on SiO2 substrates treated with self-assembled monolayers, such as hexamethyldisilazane or octadecyltrichlorosilane, aggregate spontaneously. In situ, real-time low-energy electron microscopy investigation of the morpho-logical changes in pentacene films deposited under ultrahigh vacuum reveals that the balance between pentacene film and substrate surface energies is an origin of this aggregation. With in situ atomic force microscopy - field effect transistor measurements, the authors demonstrate that field effect mobility is critically affected by this aggregation.

Suppression of nucleation around a gold electrode during pentacene growth on a SiO2 channel is found by photoemission electron microscopy. Mass flow is driven by the difference between the molecular orientations on SiO2 and gold. The poor connectivity at the channel/electrode boundary causes degradation in the performance of a field-effect transistor, which is found to be improved by self-assembled monolayer treatment on the electrode (see figure; thickness in monolayers (ML)).

large-area processability to achieve high carrier mobility with ultra-low off-currents, and very smooth surface, opening a wide window as an active semiconductor layer for the active-matrix (AM) transparent and flexible electronics. [1] Especially, indium oxide (In 2 O 3 ) based materials with the addition of zinc oxide (ZnO), gallium oxide (Ga 2 O 3 ), and tin oxide (SnO 2 ) are widely investigated for a TFT channel semiconductor for active-matrix organic light-emitting diode (AMOLED) technology. [2][3][4][5] Among them, amorphous InGaZnO (a-IGZO) becomes an industrial standard for display backplane technology. [4] But, the key issue of a-IGZO is its limited mobility because of its material disorder in the amorphous state. [4] In the hexagonal IGZO materials, crystallization of room-temperature (RT) deposited amorphous IGZO can be possible by high-temperature annealing over 700 °C. [6] On the other hand, by raising both the deposition temperature and oxygen partial pressure, a crystalline IGZO with a C axis aligned crystal orientation (CAAC-IGZO), can be obtained. It exhibits some unique properties in terms of performance such as ultra-low off-state current, close to ideal subthreshold swing (SS) because of the absence of minority carriers, which can differentiate them from the amorphous one. By having well defined CAAC crystal structure it is possible to achieve excellent TFT performance compared to the randomly orientated IGZO crystallites. The maximum reported mobility is 65.5 cm 2 V −1 s −1 for a sputtered coplanar CAAC-IGZO with a dual-gate structure. [7] Several TFT structures are investigated including back-channel etched (BCE), etch stopper inverted staggered, and self-aligned coplanar, however, the coplanar structure has the advantage of having the minimum overlap parasitic capacitance which is suitable for the large area, AMOLED displays.The requirement for a high drain current with high mobility TFT is increasing for large area, high-resolution displays. Crystalline oxide is being studied to overcome the mobility issue associated with the amorphous phase. Among them, crystalline In 2 O 3 is known as the wide bandgap (≈3.7 eV), highly Highly ordered polycrystalline indium gallium oxide (PC-IGO) film is obtained by the crystallization of room temperature sputtered amorphous IGO on a hot plate at 350 °C for 1 h and then annealed for 1 h in an N 2 O environment. A high-density PC-IGO of ≈7.15 g cm -3 with reduced oxygen vacancy (≈14.83%) and hydroxyl (OH) related defects (≈10.96%) has been obtained by N 2 O annealing. Self-aligned coplanar thin-film transistor (TFT) with the PC-IGO exhibits the average saturation mobility of 78.73 cm 2 V -1 s -1 , threshold voltage of -1.07 V, subthreshold swing of 0.147 V dec -1 , and the on/off current ratio of over 10 8 . The TFTs show excellent stability under bias-temperature stress with a negligible threshold voltage shift (ΔV TH ) of + 0.1 and -0.1 V for the positive and negative bias stresses, respectively. The TFTs exhibit very stable environmental stability when...

A poly(3-dodecylthiophene-2,5-diyl) film having in-plane anisotropic molecular arrangement was successfully fabricated by transferring its Langmuir-Blodgett film onto a step-bunched Si(111) substrate. Polarized near-edge X-ray absorption fine structure measurements revealed that the polythiophene main chains are preferentially orientated along periodic facet/terrace nanostructures on the step-bunched substrate, whereas less anisotropy was found on a flat substrate. The step-bunched Si substrate has been proved to be effective for controlling the in-plane molecular arrangement in the polymer thin film.