For applications of plasmonic structures to high performance sensors in the near-infrared region, the structures require narrowband absorption peaks, good controllability of absorption peak position, and easy fabrication process. Multiple patterns with different absorption peaks should be integrated on the same substrate. In addition, polarization independence is desired for cost reduction and miniaturization of devices. In this study, we fabricated the Si-deposited gold nano-grating structures, the wire and concentric ring structures. Then their absorption spectra were evaluated. The peak wavelength shifted to longer wavelength with increasing the pitch of the grating structure and the thickness of Si. It was revealed that the peak was greatly shifted changing the thickness of Si. In the wire structures and the concentric ring structures, polarization dependence and polarization independence of peak absorption were observed, respectively. By using the Si-deposited gold nano-grating structures, wide control of the peak wavelength was realized in the near infrared region.

We investigated the influence of the shear force on a roll-type transfer technique developed to realize high transfer ratio and high positioning accuracy. Roll-type stamping transfer is a promising method for integrating solid-state devices on flexible substrates. However, the accuracy of the roll-type stamping transfer method is insufficient for tiny devices, such as Micro-Electro-Mechanical-Systems (MEMS) sensors, integrated circuits, and surface-mounting chips, because of the shear stress that occurs at the contact of the two rolls. In this work, the shear force was measured at various roll radii and rotational speeds. The results suggest that adjustments of the roll radius can reduce the shear stress to less than 10 kPa. The low shear stress improves the misalignment angle by 2 degrees, with a high roll rotational speed, which enables the development of a hybrid sensing system for flexible and rigid devices at a large-scale.

To realize an uniformization of wiring thickness on a large size silicon probe, a design of wiring to supply current and electroplating conditions were analytically and experimentally evaluated. Circuit simulations adopted with non-linear resistance elements clarified the distribution of current density on silicon probes. The voltage drop of wiring to supply current on the silicon probe was necessary to be decreased to uniformize the thickness of wirings. Thus, the resistance of wiring to supply current were decreased, and the bypass wirings were set on the silicon probe for decreasing the current distribution. As a result, the thickness of wirings was uniformized in the thick deviation of less than 1 µm on the silicon probe units. The experiments were qualitatively consistent with the circuit simulations.

Hydrogen gas poses risks of gas leakage and explosion because the size of hydrogen molecule is very small, and its wide range of inflammability (4-75% in air). Therefore, a high-performance hydrogen sensor is indispensable for the widespread safe use of hydrogen energy. In this study, environmental resistance is improved by optimizing the current drive method of Pt ultra-thin film hydrogen sensor. The sensor output was stable even if the gas flow around the sensor changed by driving at the low current (1 mA). In addition, the sensitivity was sufficient under low current drive.