| Budget Amount *help |
¥4,940,000 (Direct Cost: ¥3,800,000、Indirect Cost: ¥1,140,000)
Fiscal Year 2016: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2015: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2014: ¥2,470,000 (Direct Cost: ¥1,900,000、Indirect Cost: ¥570,000)
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| Outline of Final Research Achievements |
Metal contacts generally show better high-bias stability under AC biases because of the time-averaging of the electromigration force under alternating currents. To observe this AC effect for single-atom contacts of metals, we carried out break-voltage and lifetime measurements on Au single-atom contacts under AC biases. For frequencies up to 100 kHz, the AC break voltage does not surpass the one at DC. The absence of the AC effect can be understood by considering the hopping of electrode atoms, the frequency of which increases with the bias and makes the time averaging of the electromigration force ineffective near the breakdown. Thus, we employed a low bias and measured the contact lifetime at 1 MHz. However, the lifetime distributions obtained at DC and 1 MHz appear the same and show no signs of the AC effect. Probably, the electromigration force is not a dominant instability mechanism at low biases and its reduction by the AC effect little affects the contact lifetime.
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