Search

The mechanism of hardness improvement of a TiZrN coating by carbon doping was investigated in terms of the residual stress and the lattice deformation. Carbon was doped using laser carburization to improve the hardness of TiZrN, which was increased from 3025 HV to 3388 HV. The lattice parameter was calculated through Rietveld refinement in order to analyze the behavior inside the lattice due to carbon doping, which showed that the parameter increased from 4.21 A to 4.44 A after the carbon doping process. The diffraction pattern was analyzed using an electron beam to identify the lattice state of the coating layer, and lattice distortion was revealed through a diffused ring pattern. The compressive residual stress was increased by 48%, which was identified through the sin2Ψ method using the lattice constant change due to carburization. After the carbon doping, the hardness of the TiZrN was increased by 10%, which was attributed to the expansion distortion generated in the TiZrN lattice and the increase of the compressive residual stress.

5-nm-scale line and hole patterning is demonstrated by synergistic integration of block copolymer (BCP) lithography with atomic layer deposition (ALD). While directed self-assembly of BCPs generates highly ordered line array or hexagonal dot array with the pattern periodicity of 28 nm and the minimum feature size of 14 nm, pattern density multiplication employing ALD successfully reduces the pattern periodicity down to 14 nm and minimum feature size down to 5 nm. Self-limiting ALD process enable the low temperature, conformal deposition of 5 nm thick spacer layer directly at the surface of organic BCP patterns. This ALD assisted pattern multiplication addresses the intrinsic thermodynamic limitations of low χ BCPs for sub-10-nm scale downscaling. Moreover, this approach offers a general strategy for scalable ultrafi ne nanopatterning without burden for multiple overlay control and high cost lithographic tools.

We thank G. S. Kim and J.-H. Ahn for assistance with thin film depositions, and S. S. Bae for assistance with SEM analysis. This work was supported by the second stage of the Brain Korea 21 Project, the Korea Research Foundation (KRF-2005-003-D00085), the Basic Research Program of the Korea Science & Engineering Foundation (R01-2005- 000-10456-0), the Korean Ministry of Science and Technology, and the Korean Ministry of Science and Technology and Fundamental R&D Program for Core Technology of Materials funded by the Korean Ministry of Commerce, Industry and Energy. Also, this work was partially supported by grants-in-aid for the National Core Research Center Program from MOST/KOSEF (No. R15-2006-022-01001-0).

Small machines are highly promising for future medicine and new materials. Recent advances in functional nanomaterials have driven the development of synthetic inorganic micromachines that are capable of efficient propulsion and complex operation. Miniaturization and large-scale manufacturing of these tiny machines with true nanometer dimension are crucial for compatibility with subcellular components and molecular machines in operation. Here, block copolymer lithography is combined with atomic layer deposition for wafer-scale fabrication of ultrasmall coaxial TiO2/Pt nanotubes as catalytic rocket engines with length below 150 nm and a tubular reactor size of only 20 nm, leading to the smallest man-made rocket engine reported to date. The movement of the nanorockets is examined using dark-field microscopy particle tracking and dynamic light scattering. The high catalytic activity of the Pt inner layer and the reaction confined within the extremely small nanoreactor enable highly efficient propulsion, achieving speeds over 35 µm s−1 at a low Reynolds number of