Massive aligned carbon nanotubes hold great potential but also face significant integration/assembly challenges for future beyond-silicon nanoelectronics. We report a wafer-scale processing of aligned nanotube devices and integrated circuits, including progress on essential technological components such as wafer-scale synthesis of aligned nanotubes, wafer-scale transfer of nanotubes to silicon wafers, metallic nanotube removal and chemical doping, and defect-tolerant integrated nanotube circuits. We have achieved synthesis of massive aligned nanotubes on complete 4 in. quartz and sapphire substrates, which were then transferred to 4 in. Si/SiO(2) wafers. CMOS analogous fabrication was performed to yield transistors and circuits with features down to 0.5 mum, with high current density approximately 20 muA/mum and good on/off ratios. In addition, chemical doping has been used to build fully integrated complementary inverter with a gain approximately 5, and a defect-tolerant design has been employed for NAND and NOR gates. This full-wafer approach could serve as a critical foundation for future integrated nanotube circuits.

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Coexistence of metallic and semiconducting carbon nanotubes in as-grown samples sets important limits to their application in high-performance electronics. We present the metal-to-semiconductor conversion of carbon nanotubes for field-effect transistors based on both aligned nanotubes and individual nanotube devices. The conversion process is induced by light irradiation, scalable to wafer-size scales and capable of yielding improvements in the channel-current on/off ratio up to 5 orders of magnitude in nanotube-based field-effect transistors. Inactivation of metallic nanotubes in the channels was achieved as a consequence of a diameter-dependent photochemical process that led to a controlled oxidation of the nanotube sidewall and, hence, stronger localization of pi-electrons. Optimization of irradiation conditions yields nearly 90% of depletable nanotube field-effect transistors.

Supporting InformationSupporting Information Available: S1. Detailed calculation of the geometrical factor S(α,φ) for packed monolayer and bilayer nanospheres; S2. Detailed calculation of the catalyst nanoparticle size with different deposition angles and different packed nanosphere structures; S3. AFM image and diameter distribution of catalyst arrays prepared using packed bilayers of 100 nm nanospheres; S4: Raman spectrum of nanotubes showing negligible D-band and RBM mode.

Atomic force microscopy (AFM), scanning electron microscopy (SEM), white light imaging measurements, and Raman microscopy were employed for the characterization of hexahydro-1,3,5-trinitro-1,3,5-s-triazine (RDX) nanoparticles deposited on glass substrate surfaces. The RDX nanoparticles were prepared by exposure of glass substrate surfaces to an aerosol jet containing RDX. The spectroscopic signature of RDX particles and the two known forms of the material, β and R RDX, are compared. Raman measurements reveal that RDX nanoparticles and β deposits have similar spectroscopic signatures between 750 and 1000 cm -1 .