This work investigates advanced single-electron transistor (SET) devices for detection of charge motion in solid-state systems. In particular, novel, nanoscale twin-SET and double-island SET (DISET) detectors are introduced as sensitive charge detectors. Some advantages over conventional SET detectors in terms of noise performance, sensitivity and versatility are pointed out. With the prospect of present, transistor-based microelectronics facing serious limitations due to quantum effects and heat dissipation, alternative computing paradigms ??? such as quantum computers, quantum-dot cellular automata and single-electronics ??? have emerged, promising an extension of highlevel integration and computing power beyond the above limitations. The most promising proposals are based on solid-state systems, and readout of a computational result often requires ultra-sensitive charge detectors capable of sensing the motion of single charges on fast timescales. SETs have been shown to combine all these qualities. However, random fluctuations of the background charge in solid-state systems can affect SETs and cause errors during readout. A twin-SET detector is presented that consists of two independent SETs, which were used to detect controlled single electron transfers on a small, floating metal double-dot. By cross-correlating the two SET signals, rejection of random charge noise is successfully demonstrated, thus decreasing the error probability during readout. Detection of single-electron transfer in a double-dot is also demonstrated using a double-island SET. In addition, conductance suppression in this novel DISET detector allows the detection of electrostatically degenerate charge con- figurations of a double-dot, which cannot be achieved with single-island SETs. We consider the noise performance of the DISET, and an intuitive definition of the DISET charge sensitivity suggests that under certain conditions, DISETs can have a better charge sensitivity than conventional SETs, which would be attractive for quantum limited measurements. Finally we present the first study of a DISET operated at radio-frequencies (rf-DISET), compatible with charge detection on ms timescales. This capability is a prerequisite when reading out the charge state of quantum mechanical systems. A very good charge sensitivity (5.6 x 10i6 e/pHz) and noise temperature (2.1 K) of the rf-DISET setup are reported.
| Identifer | oai:union.ndltd.org:ADTP/282699 |
| Date | January 2004 |
| Creators | Brenner, Rolf, Physics, Faculty of Science, UNSW |
| Publisher | Awarded by:University of New South Wales. School of Physics |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | Copyright Rolf Brenner, http://unsworks.unsw.edu.au/copyright |
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