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Metal-stable excited states in closed quantum dot probed by Al-SET

Sep 19 2006 Condensed Matter Seminar Department of Physics / NTHU. Metal-stable excited states in closed quantum dot probed by Al-SET. Jeng-Chung Chen. Metal-stable excited states in closed Device characterization Excited electronic states in closed QD Discussion Conclusion

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Metal-stable excited states in closed quantum dot probed by Al-SET

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  1. Sep 19 2006 Condensed Matter Seminar Department of Physics / NTHU Metal-stable excited states in closed quantum dot probed by Al-SET Jeng-Chung Chen

  2. Metal-stable excited states in closed • Device characterization • Excited electronic states in closed QD • Discussion • Conclusion • On-chip optical-coupled QH devices • Passive THz scanning microscopes • Emitter: Hot spots • Detector QH detector • Device design • Future perspective Outline

  3. Introduction: Technological and biological length scales

  4. Single Electron Transistor - Introduction SEM picture 100nm Lateral Confinement Technique Capacitive Charging Model Shadow Evaporation Technique Eg. diameter ~ 0.5-0.2m Cg ~100-10 aF C ~2-0.9 fF Al

  5. Device Characterization Lithographic size of QD : 570nm560nm Temperature: 70-100mK (a)

  6. Meta-stable states of QD observed by Al-SET

  7. Qualitative Discussion F0 V1=-1.18V

  8. Discussion: Emperical Model V1=-1.18V fixed In closed QD, regime 2-6

  9. Quantitative discussion U1 U2 UQD Cc~58.8aF, C1sg2=3.12aF

  10. Conclusion – First part • Kinetics of charging and discharging of closed quantum dots (QD)in a GaAs/AlGaAs heterostructure crystal are studied by anAluminum single electron transistor (Al-SET) electrostaticallycoupled to the quantum dot. • The period and conductance of CB peaksof Al-SET associated with different gating conditions revealseveral distinct regimes, strongly depending on the tunnelingbarriers of QD. • A lift-up and an uncovered sinking electronexcited state with long life time are realized in the completelyclosed dot. • An empirical model is proposed to explain the physicalorigins of these transitions. Ref: J.C. Chen, et al. Phys. Rev. B, 74, 045321 (2006).

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