Abstract
Single charge effects attract much attention with respect to possible applications as future transistor structures or for quantum cryptography. Here, surface acoustic wave mediated single charge transport through quantum dots (QDs) formed in a carbon nanotube (CNT) is presented. The CNT bridges metallic source and drain contacts on a piezoelectric host substrate, employing an acoustic alignment technique. The metal electrodes in contact with the nanotube provide tunnel barriers to the quasi one-dimensional electron system, hence forming a few QD in series due to the presence of defects within the CNT. The dynamic piezoelectric field associated with the surface wave leads to an acoustoelectric current through the system which turns out to be quantized like in a turnstile device.
Highlights
Can tunnel into the quantum dots (QDs) from the source
In conclusion we have presented measurements on carbon nanotube (CNT) that were confined to QDs by the contacting mechanism
Due to the length of the contacted CNT being less than a micrometre and a high two-terminal resistance, the assumption of dimensionality reduction to QDs is justified
Summary
Two samples (in the following denoted as sample A and B) were prepared on lithiumniobate-substrate (LiNbO3 128-Y-cut-X-propagation) by standard electron-beam lithography. For about 20 min, a radio frequency signal of P = 16 dBm power and the respective IDT resonant frequency f1 was applied to the low frequency IDT1 in order to launch a SAW with large amplitude. This large amplitude SAW is used to successfully align the CNT with respect to the contact pattern. For the case of a metalized surface the piezoelectric SAW fields are efficiently screened leaving a large field gradient directly at the edges of the metal electrodes In this sense, the SAW driven alignment procedure is similar to the dielectrophoresis process for CNT alignment presented in [12]
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