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We studied an advanced drift layer design which has an intermediate layer in mesa region for two-step-oxide field-plate MOSFET. The intermediate layer is formed by a high energy ion-implantation via source contact window. By TCAD simulation, it was confirmed the intermediate layer can decrease depletion layer capacitance in lower drain voltage. There was no change of breakdown voltage, and on-resistance (R ON A) increased slightly with increasing the implantation energy. An attractive effectiveness was obtained as gate-drain charge (Q GD ) decrease, and output charge and reverse recovery charge were slightly decreased. Evaluated performances showed that the Q GD and R ON Q GD were reduced by 14.1% and 10%, respectively. In power loss estimation of an assumed circuit, it was observed the newly designed FP-MOSFET can improve total power loss, especially in high-speed switching.

Silicon carbide (SiC) has attracted increasing attention as a material suitable for use with high breakdown voltages and at high temperatures. The effects of residual stress and thermal stress on the electrical properties are therefore a matter of growing concern. To analyze the effects, multi-physics simulation is required. The aim of this study is to present an evaluation method for SiC power modules by electro-thermal-stress coupled analysis. In this analysis, we investigate the relationship among mechanical stress, temperature, and electrical resistance in 4H-SiC MOSFET. To investigate the relationship, we used a four-point bending system that is capable of applying uniaxial stress to the SiC device. We prepared two kinds of test specimens with the uniaxial stress direction of four-point bending coinciding with the 〈112̄0〉 and 〈11̄00〉 direction of SiC. To associate the four-point bending load with the stress components in the SiC device, the four-point bending test was simulated by the finite element method. Tensile or compressive load was applied to two types of test specimens, and the internal stress of the SiC device was determined. To determine the internal stress during operation and mounting, the simple module model was also simulated by the structural analysis method. The internal stress was simulated from mounting temperature to the operating temperature. An electrical circuit and thermal circuit were constructed for the DC-DC converter in the above-described module for the coupled analysis method. The relationship among mechanical stress, temperature, and electrical resistance was incorporated into the additional resistance of the MOSFET in the electrical circuit. When an isotropic stress from −500 to 1400 MPa was applied with the SiC under the oxide film in the one parallel DC-DC converter, the change in the power conversion efficiency was about 0.16%. This indicates that our proposed method is a useful simulation method for SiC power modules.

Nanoscale geometric devices, which penetrate cells, offer numerous intracellular applications. DNA injection into a cell has potential to genetically alter the function of living brain cells. However, nanowire (or nanotube) — based conventional intracellular devices have been limited to cultured cells, due to the short wire length of

This paper reports a new lithography method using thin-film edge electrodes (TEEs) to collectively transfer nanopatterns by generating oxide on the substrate surface via an electrochemical reaction (ECR). Nanometric thick TEEs are formed on the sidewall of insulating stamping structures. ECR-based oxide patterns have the same width and shape as the TEEs because ECR is induced only between the conductor and the substrate. Oxide nanopatterns of 300 nm and 70 nm in width were collectively transferred on Si substrate in a millimeter-scale area.

Here we report vertical metal/silicon dioxide (SiO2) multiwalled microtube arrays as electrical and optical neuroprobes for “optogenetic”. Three-dimensional metal/SiO2-microtube arrays can be fabricated by vapor-liquid-solid (VLS) growth of silicon-wire, followed by the SiO2/metal depositions and the core-silicon etching. As the inside metal, we use iridium (Ir) with a low electrical electrolyte/electrode interfacial impedance in saline. An optical propagation through the Ir/SiO2-tube calculated by finite-difference time-domain (FDTD) method clearly indicates the effect of the inside Ir on the improved locality of light stimuli with the spot diameter of

We demonstrated batch, pinpoint, and multisite-transfer of nanoparticles via vertically-aligned nanotip silicon probe arrays for powerful applications of nanoinjectors, including local drug delivery and DNA transfer into biological samples (e.g., cell, neuron and tissue). Although several nanoinjections have been demonstrated using “nanoprobe” (e.g., glass pipette, silicon nanowire and carbon nanotube [1–3]), the common issues of these devices are the limitation of the probe number, short length and robustness of the probe section. In order to solve these issues, we propose a nanoinjector, based on a vertical nanotip probe array with a high aspect ratio. Here, we demonstrated electrical batch trappings of nanoparticles at positive biased nanotips, and the trapped nanoparticles were released by ultrasonic vibration. These preliminary results indicate the nanoparticle transfer capability of the nanotip probes for use in multisite deep nanoinjections on numerous biological samples.

In this paper, we present out-of-plane micro-scale diameter light guiding silicon dioxide tube arrays for use in optical stimulation of neurons. An optical propagation through the dioxide tube was calculated by using finite-difference time-domain (FDTD) simulation. Based on the calculated result, we designed and fabricated 3-µm-inner diameter 24-µm-height silicon dioxide tube arrays with the wall thickness of 0.5 µm, using selective vapor-liquid-solid (VLS) growth of silicon microwire, followed by microfabricating processes. The optical transmission capability of the fabricated tube was experimentally confirmed by using light of 470 nm, 525 nm, and 595 nm in wavelength.

We developed out-of-plane, high aspect ratio, nanoscale tip silicon microwire arrays for application to penetrating, multisite, nanoscale biological sensors. Silicon microwire arrays selectively grown by gold-catalyzed vapor-liquid-solid growth of silicon can be formed to create sharpened nanotips with a tip diameter of less than 100 nm by utilizing batch-processed silicon chemical etching for only 1-3 min. The tip angles achieved ranged from 11 degrees to 38 degrees. The nanotip silicon microwires can perform gelatin penetration without wire breakdown, indicating their potential penetrating capability for measurements inside biological tissues.

We developed integration and three-dimensional (3D)-fabrication techniques to nanoscale-tip silicon-microprobe arrays for multiple electrical nano-measurement systems with a high aspect ratio. Vapor-liquid-solid (VLS) grown vertically-aligned 120µm-length silicon microprobe arrays (2µm-diameter), each with nanoscale-tip by controlling the silicon-etching (less than 100-nm-diameter, radius of curvature 50nm), have been integrated with IC-processed interconnections. Subsequently, the nanotip silicon probe is entirely covered with Pt/Ti and encapsulated with an insulator, SiO 2 . In addition, herein we proposed the use of a spray-coating of photoresist and cycled etchings of the photoresist/SiO 2 at the probe-tips. Consequently, the nanotips can precisely be patterned and etched, resulting in the exposed Pt/Ti/silicon-nanotip with a controlled height of 2µm.

We developed a batch-fabrication of nanoscale-tip silicon microprobe arrays for use in multipoint nanoscale investigations of cell/neuron in-vivo/in-vitro. Sharpened tips, less than 100nm diameter, can be formed at the tips of out-of-plane three-dimensional silicon microprobe (length ≫10?m) arrays, by silicon wet etching-based batch-process within only 1-3min, providing precisely controlled tip angles ranging from 15° to 50°. The penetration capability of the nanoscale-tip microprobes was demonstrated, using finite element modeling (FEM) simulations and penetration tests with a gelatin as tissue/cell.