Budget Amount *help |
¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000)
Fiscal Year 2011: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000)
Fiscal Year 2010: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2009: ¥2,340,000 (Direct Cost: ¥1,800,000、Indirect Cost: ¥540,000)
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Research Abstract |
We studied elemental technologies to develop HTS(high temperature superconducting) nano-wire as a key device "single photon detector" for the quantum cryptographic communication. Experiments were carried out using YBa_2Cu_3O_y(YBCO). It was shown that a 200-nm-wide and 25-mm-long nano-wire could be constructed in a 100μm×100μm square by using a 250-turns-meandering configuration. We examined how to suppress superconductivity degradation in the nano-wire during plasma etching processes. Liquid N2 cooling to a sample stage was effective to prevent the degradation from ion bombardments of plasma etching. As a result, superconducting current was observed for a 200-nm-wide and 1-μm-long nano-wire. We also investigated lattice mismatching at a hetero-epitaxial surface between YBCO and single crystal substrate. Then, YBCO thin film with only 20 nm thickness showed critical temperature(T_c) over 80 K. On the other hand, a T_c dependence on the YBCO thickness was examined from 80 nm to 10 nm. It produced a possibility to realize very thin HTS nano-wire with effective thickness less than 10 nm.
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