Conjugated polymers, such as polyfluorene and poly(phenylene vinylene), have been used to selectively disperse semiconducting single-walled carbon nanotubes (sc-sWnTs), but these polymers have limited applications in transistors and solar cells. Regioregular poly(3-alkylthiophene)s (rr-P3ATs) are the most widely used materials for organic electronics and have been observed to wrap around sWnTs. However, no sorting of sc-sWnTs has been achieved before. Here we report the application of rr-P3ATs to sort sc-sWnTs. Through rational selection of polymers, solvent and temperature, we achieved highly selective dispersion of sc-sWnTs. our approach enables direct film preparation after a simple centrifugation step. using the sorted sc-sWnTs, we fabricate high-performance sWnT network transistors with observed charge-carrier mobility as high as 12 cm 2 V − 1 s − 1 and on/off ratio of > 10 6 . our method offers a facile and a scalable route for separating sc-sWnTs and fabrication of electronic devices.

Tuning the threshold voltage of a transistor is crucial for realizing robust digital circuits. For silicon transistors, the threshold voltage can be accurately controlled by doping. However, it remains challenging to tune the threshold voltage of single-wall nanotube (SWNT) thin-film transistors. Here, we report a facile method to controllably n-dope SWNTs using 1H-benzoimidazole derivatives processed via either solution coating or vacuum deposition. The threshold voltages of our polythiophene-sorted SWNT thin-film transistors can be tuned accurately and continuously over a wide range. Photoelectron spectroscopy measurements confirmed that the SWNT Fermi level shifted to the conduction band edge with increasing doping concentration. Using this doping approach, we proceeded to fabricate SWNT complementary inverters by inkjet printing of the dopants. We observed an unprecedented noise margin of 28 V at V DD = 80 V (70% of 1/2V DD ) and a gain of 85. Additionally, robust SWNT complementary metal−oxide−semiconductor inverter (noise margin 72% of 1/2V DD ) and logic gates with rail-torail output voltage swing and subnanowatt power consumption were fabricated onto a highly flexible substrate. nanomaterials | n-doping | inkjet-printed | CMOS circuit F lexible electronics have attracted increasing attention recently due to the plethora of possible and realized applications in radio-frequency identification cards (1, 2), flexible displays (3, 4), and digital processors (5). Solution-processed single-walled carbon nanotubes (SWNTs) are a promising candidate for flexible circuits due to their high charge carrier mobility (6), excellent flexibility/stretchability (7-9), and their compatibility with lowcost, large-area manufacturing processes, such as printing (1, 10) of SWNTs. Their applications in thin-film transistors (TFTs) and integrated logic circuits (11-14) have been demonstrated. However, to achieve robust digital circuits with high immunity against the influence of electronic noise in the system, it is important to be able to control the specific value of the threshold voltage of a transistor during the fabrication process (15,16). This is because transistor threshold voltage determines the input voltage at which a circuit switches between two logic states (trip voltage of an inverter). When the trip voltage is half of the supply voltage, the circuit has the largest noise margin, which is a quantitative measure of the immunity of a logic circuit against noise and a figure of merit to characterize the robustness of the circuit (17, 18). If threshold voltage cannot be controlled during the fabrication process, the resulting circuit might not work reliably due to the electrical noise that is always present in the system. Because SWNTs have ambipolar electrical transport properties (19), accurately tuning the threshold voltage permits the construction of complementary metal−oxide−semiconductor (CMOS) circuits that use both the p-type and n-type character of SWNTs. The advantages of CMOS circuits compared with unipolar ...

Plasma enhanced chemical vapor deposition Si-rich silicon oxynitride films for advanced self-aligned contact oxide etching in sub-0.25 μm ultralarge scale integration technology and beyond Fully large-scale integration-process-compatible Si field emitter technology with high controllability of emitter height and sharpness J. Vac. Sci. Technol. B 15, 488 (1997); 10.1116/1.589605 Pattern profile control of polysilicon in magnetron reactive ion etching J. Vac. Sci. Technol. B 15, 221 (1997); 10.1116/1.589268 Effect of plasma polymerization film on reducing damage of reactive ion etched silicon substrates with CHF3+O2 plasmas J.The etch rates of SiO 2 , photoresist, Si, and SiN in a 27 MHz reactive ion etching system at constant ion flux of 6ϫ10 16 cm Ϫ2 s Ϫ1 and ion energy of 1450 V were studied. Typical incident flux densities of CF 2 and CF ϩ were on the order of 10 17 and 10 16 cm Ϫ2 s Ϫ1 , respectively. The SiO 2 etch rate was determined by the balance of the energy supplied by the total ion flux and the amount of the C-F reactive species supplied by radicals and ions. When we roughly assumed the surface reaction probabilities of F, CF, CF 2 and CF 3 to be 0.1, 0.1, 0.1, and 0.5, the SiO 2 etch rate could be expressed well as a function of the total number of F in the net radical fluxes. To clarify the dominant flux including radicals and ions, however, further research on surface reaction probabilities on the actual etched surface must be conducted because the incident fluxes strongly depend on these constants of the surface reaction probability. Lowering the total ion flux or ion energy decreased the etch rate of SiO 2 . A higher ion flux or higher ion energy is required to obtain higher etch yields. When excess C-F reactive species exist on the etched surface, they disturb the etching reaction by wasting the energy of incident ions. Under these conditions, a reactive species is no longer an ''etchant,'' but an ''inhibitor.'' Therefore, it is important to control the amount of total reactive species according to the ion conditions. Oxygen contributed to the removal of these excess C-F species, resulting in a higher etch yield. In contrast, the etch rates of a photoresist, Si, and SiN did not depend on flux of the C-F reactive species, but on the oxygen concentration. It is concluded that a process with high selectivity requires low oxygen concentration, high ion flux, and optimized flux of C-F reactive species.

Polymers having both epoxy moieties and thermally cleavable tertiary ester moieties in the side chain were synthesized and characterized. On UV irradiation, polymer films containing photoacid generators (PAG) such as 9-fluorenilideneimino p-toluenesulfonate (FITS) and triphenylsulfonium triflate (TPST) became insoluble in tetrahydrofuran. The insoluble fraction of the irradiated films was increased by postexposure-baking at 90 °C if FITS was used as a PAG. When the cross-linked polymer films were baked at 160−180 °C, they became soluble in methanol. The effective baking temperature was dependent on the type of PAG used and on the polymer structure. Thermal degradation of the photochemically induced network polymers was studied by FT−IR spectroscopy, TGA analysis, and film thickness changes.

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The radicals of capacitive plasmas actually used in mass production were analyzed using various measurement systems. The composition of radicals in bulk plasma depends on the gas chemistry, the dissociation process, and interaction with the wall. It is revealed that parent gas (C4F8) is dissociated by multiple collision with electrons according to τ·n e<σv>, where τ is the residence time, n e is the electron density, σ is the dissociation collision cross section and v is the electron velocity. A high-performance etching process, which can realize 0.09 µmφ contact holes with aspect ratio of 11, was achieved using a short residence time to suppress the excess dissociation and the control of deposition species through the addition of O2 to C4F8/Ar plasma as well as the reduction of the density of F radicals through the reaction with the Si wall.

To investigate the mechanism of C4F8 dissociation in parallel-plate-type plasma, we used several of the latest diagnostic tools and made extensive measurements of electrons, radicals, and ions under conditions that greatly suppressed the effects of plasma-surface interaction. These measurements showed that the amount of light fluorocarbon radicals and ions increased with increasing electron density. The dissociation of C4F8 was analyzed by using rate equations, after confirming the stability and uniformity of the plasma. The total dissociation rate coefficient of C4F8 was 1×10−8 cm3/s, and CF2 radicals were mainly generated from products of C4F8 dissociation. F was mainly generated from CF2 by electron-impact dissociation and lost by pumping. We could estimate that the C2F4 density was roughly comparable to the densities of CF and CF3, and that the surface loss probability of C2F4 increased with increasing electron density. C2F4 might play an important role in the etching because of its rich polymerization characteristics.

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