Boundary Scattering in Ballistic Graphene

We report magnetotransport measurements in ballistic graphene/hexagonal boron nitride mesoscopic wires where the charge carrier mean free path is comparable to wire width $W$. Magnetoresistance curves show characteristic peak structures where the peak field scales with the ratio of cyclotron radius $R_\textrm{c}$ and wire width $W$ as $W/R_\textrm{c} = 0.9 \pm 0.1$, due to diffusive boundary scattering. The obtained proportionality constant between $R_\textrm{c}$ and $W$ differs from that of a classical semiconductor 2D electron system where $W/R_\textrm{c} = 0.55$.Comment: 14 pages, 4 figure

51. Dynamics of Ions in Nematic Liquid Crystals(poster presentation,Soft Matter as Structured Materials)

この論文は国立情報学研究所の電子図書館事業により電子化されました。ネマチック液晶中の荷電粒子が与える静的、および動的な効果について、Ginzburg-Landau理論の枠組を用いて議論する。(i)ネマチック相にある液晶に荷電粒子を配した場合の、配向秩序の変形、およびその結果としての欠陥生成について調べた。特に荷電粒子の及ぼす寄与が強い場合、粒子近傍で電荷誘起のアンカリング現象が期待される。(ii)定常電場、および振動電場を与えた場合の、ネマチック液晶中の荷電粒子の運動について調べた。我々の数値計算の結果は、電荷の効果が顕著になるに従い、移動度が小さくなることを予測する。これは、電荷の効果が強くなるにつれ、配向秩序が変形する空間領域が拡大するため、有効的な流体半径が増大すると理解できよう。また、多数の荷電粒子が液晶に浸されている場合の複雑な現象に付いても、併せて報告したい

Development of Gentle Slope Light Guide Structure in a 3.4 μm Pixel Pitch Global Shutter CMOS Image Sensor with Multiple Accumulation Shutter Technology

CMOS image sensors (CISs) with global shutter (GS) function are strongly required in order to avoid image degradation. However, CISs with GS function have generally been inferior to the rolling shutter (RS) CIS in performance, because they have more components. This problem is remarkable in small pixel pitch. The newly developed 3.4 µm pitch GS CIS solves this problem by using multiple accumulation shutter technology and the gentle slope light guide structure. As a result, the developed GS pixel achieves 1.8 e− temporal noise and 16,200 e− full well capacity with charge domain memory in 120 fps operation. The sensitivity and parasitic light sensitivity are 28,000 e−/lx·s and −89 dB, respectively. Moreover, the incident light angle dependence of sensitivity and parasitic light sensitivity are improved by the gentle slope light guide structure

Microstructures of 50-nm Cu Interconnects along the Longitudinal Direction

Grain size distributions and average grain sizes in the longitudinal direction of the Cu interconnect in 50-, 70- and 80-nm-wide Cu interconnects were evaluated and compared with the resistivities of each interconnect. After annealing, the standard deviation of grain sizes for 50-nm Cu interconnect increased to 27.5, and the average grain size microstructure grew to larger than that of as-deposited 50-nm Cu interconnects. The value of standard deviation of grain sizes in the normal distribution histogram for a 50-nm wire was found to be much smaller than those for 70- and 80-nm Cu wires after annealing. This implies that adequate grain growth should not be expected in the very narrow Cu interconnects (less than 50-nm) of the future if they are made with the conventional annealing process. [doi:10.2320/matertrans.MRA2007611