Here we report the directed growth of ZnO nanowires on multilayer graphene films (MGFs) without the use of metal seed materials. The ZnO source substance was diffused onto the MGF surface, where nanowires tended to grow in the high surface energy sites. This property was exploited to fabricate top-gate structural nanowire transistors with ZnO nanowires grown in the direction of the exposed sides of 6 × 4 μm patterned MGFs with a SiO2 capping layer. The devices showed an on-current of 160 nA, a threshold voltage of −2.27 V, an on-off current ratio of 3.98 × 105, and a field effect mobility of ∼41.32 cm2/V·s.

We have investigated the change in structural and electrical properties of In(2x)Ga(2-2x)O(3) nanowires (x = 1, 0.69 and 0.32) grown with varied indium (In) and gallium (Ga) contents. The as-grown In(2x)Ga(2-2x)O(3) nanowires kept the cubic crystal structure of In(2)O(3) intact even when the atomic percentages of Ga were increased to 31% (x = 0.69) and 68% (x = 0.32) in comparison to the total amount of In and Ga. However, as Ga added to In(2)O(3) structure was substituted with In, the lattice constant decreased and, consequently, the main peaks observed in x-ray diffraction in the direction of (222), (400) and (440) shifted by around ∼0.08°. The average threshold voltage values for the In(2x)Ga(2-2x)O(3) nanowire transistors were -9.9 V (x = 1), -6.6 V (x = 0.67) and -5.6 V (x = 0.32), exhibiting a more positive shift and the sub-threshold slope increased to 0.53 V /dec (x = 1), 0.33 V /dec (x = 0.67) and 0.27 V /dec (x = 0.32), showing an improved switching characteristic with increasing Ga.

The development of display scan drivers is an essential step in the effort to develop transparent and flexible display devices based on nanowire transistors. Here we report a transparent nanowire-based shift register that functions as the standard logic circuit of a display scan driver. To form the shift register circuits using only n-type nanowire transistors, a novel circuit structure was introduced to avoid the output voltage drop typical of purely n-type circuits. A circuit simulation based on the measured nanowire transistor characteristics was developed in the planning phase to verify the circuit operation of the shift register. The shift register successfully produced an output of 0-3 V without an output voltage drop while applying an input of 3 V peak to peak. In addition, the shift register was designed to have multiple channels with a randomly oriented nanowire placement method to enhance the operation yield.

The amount of oxygen vacancies on the surface of SnO 2 nanowires was controlled by N 2 plasma. Nitrogen ions in N 2 plasma were substituted for oxygen vacancies (V o ) on the nanowire surface, reducing the amount of oxygen vacancies. Photoluminescence spectra showed that the V o -related peak around 600 nm decreased dramatically after N 2 plasma and increased again after ultravioletozone (UVO) treatment. The threshold voltage (V th ) of the SnO 2 nanowire transistors exhibited a þ1.8 V positive shift after N 2 plasma, and the V th of the N 2 plasma-treated nanowire transistors shifted toward the negative direction (À0.76 V) again after UVO.Oxide nanowires are applied in various fields including nanoscale electronics, next-generation displays, photovoltaic devices, and gas/solar sensors due to their outstanding characteristics such as wide-energy band gaps, nano-scale integration, optical transparency, mechanical flexibility, low voltage operation, and high mobility. [1][2][3][4] Most notably, studies are currently focusing on oxide nanowires applied to commercial electronic circuits and, in particular, integrated transistor circuits. 5-7 For such applications, it is crucial to effectively control the transistor characteristics of the oxide nanowires to meet required specifications of integrated transistor circuits. Therefore, nanowire characteristics should be controlled and monitored continuously through a device optimization process. In related studies, various methods, such as optimizing the growth conditions of nanowires, doping nanowires with various materials, and controlling characteristics through post-treatments after producing nanowire devices, are being applied. 8-10 Among these methods, post-treatments are relatively simple, easy to control, and ensure reproducibility. Various attempts have recently been made to control characteristics through post-treatment of the nanowire surface using thermal annealing, H 2 , O 2 , Ar plasma, and ozone treatment. In an oxygen atmosphere, the field emission of ZnO was enhanced through thermal annealing. 11 ZnO nanowire treated by Ar or H 2 plasma showed improved conductivity. 12,13 In addition, surface treatment using ultraviolet (UV) radiation enabled temporary interface treatment. 14 However, these attempts were only applied to the observation of nanowire properties after the posttreatment, not to the fine control of the characteristics of nanowire devices.In this study, N 2 plasma was used to control the characteristics of SnO 2 nanowire transistors (NWTs) by controlling the characteristics of the SnO 2 nanowire surface. The amount of oxygen vacancies (V o ), which act as current paths in semiconducting oxide nanowires, were determined during the initial growth stage of crystal formation; this stage determines the threshold voltage (V th ), subthreshold slope (SS), and mobility characteristics of oxide NWTs. But, N 2 plasma successfully controlled transistor characteristics of NWT devices, including V th , by controlling V o on the surface of oxide nanowires afte...

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