BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//THOMAS YOUNG CENTRE - ECPv6.15.17//NONSGML v1.0//EN
CALSCALE:GREGORIAN
METHOD:PUBLISH
X-WR-CALNAME:THOMAS YOUNG CENTRE
X-ORIGINAL-URL:https://thomasyoungcentre.org
X-WR-CALDESC:Events for THOMAS YOUNG CENTRE
REFRESH-INTERVAL;VALUE=DURATION:PT1H
X-Robots-Tag:noindex
X-PUBLISHED-TTL:PT1H
BEGIN:VTIMEZONE
TZID:Europe/London
BEGIN:DAYLIGHT
TZOFFSETFROM:+0000
TZOFFSETTO:+0100
TZNAME:BST
DTSTART:20250330T010000
END:DAYLIGHT
BEGIN:STANDARD
TZOFFSETFROM:+0100
TZOFFSETTO:+0000
TZNAME:GMT
DTSTART:20251026T010000
END:STANDARD
BEGIN:DAYLIGHT
TZOFFSETFROM:+0000
TZOFFSETTO:+0100
TZNAME:BST
DTSTART:20260329T010000
END:DAYLIGHT
BEGIN:STANDARD
TZOFFSETFROM:+0100
TZOFFSETTO:+0000
TZNAME:GMT
DTSTART:20261025T010000
END:STANDARD
BEGIN:DAYLIGHT
TZOFFSETFROM:+0000
TZOFFSETTO:+0100
TZNAME:BST
DTSTART:20270328T010000
END:DAYLIGHT
BEGIN:STANDARD
TZOFFSETFROM:+0100
TZOFFSETTO:+0000
TZNAME:GMT
DTSTART:20271031T010000
END:STANDARD
END:VTIMEZONE
BEGIN:VEVENT
DTSTART;TZID=Europe/London:20260601T140000
DTEND;TZID=Europe/London:20260601T160000
DTSTAMP:20260529T201222
CREATED:20260529T161040Z
LAST-MODIFIED:20260529T161041Z
UID:7933-1780322400-1780329600@thomasyoungcentre.org
SUMMARY:UCL / LCN Seminar: Measuring properties of single defects\, dopants and quantum dots with nm spatial resolution - Prof. Peter Grütter\, McGill University
DESCRIPTION:UCL / LCN Seminar: Measuring properties of single defects\, dopants and quantum dots with nm spatial resolution – Prof. Peter Grütter\, McGill University Share on X\n\n\n\n\n\n\n\n\nPeter is a visitor at the LCN until 5 June\, so if you would like to meet him you can contact me\, or him directly\, please contact Neil Curson (n.curson@ucl.ac.uk). \n\n\n\nSemiconductor interfaces often have isolated trap states which modify electronic properties. We have developed a framework to quantitatively describe a metal-insulator semiconductor (MIS) device formed out of a metallic AFM tip\, vacuum gap\, and semiconducting sample. This framework allows the measurement of local dopant concentration\, bandgap and band bending timescales with nm scale resolution of different defects on semiconductors such as 2D MoSe2\, Si and pentacene monolayers [1]. \n\n\n\nSpecifically\, we have characterize individual defects at the Si-SiOx interface. We show that surface charge equilibration timescales\, which range from 1−150 ns\, increase significantly around interfacial states [2]. From this we conclude that dielectric loss under time-varying gate biases in metal-insulator-semiconductor capacitor device architectures is highly spatially heterogeneous over nm length scales. We have also analyzed two-state fluctuations localized at these interfacial traps\, exhibiting bias-dependent rates and amplitudes. When measured as an ensemble\, these observed defects have a 1/f power spectral trend at low frequencies [3]. Low-frequency noise due to two level fluctuations inhibits the reliability and performance of nanoscale semiconductor devices\, and challenges the scaling of emerging qubits. The presented method and insights provide a more detailed understanding of the origins of 1/f noise in silicon-based classical and quantum devices\, and could be used to develop processing techniques to reduce two-state fluctuations associated with defects. \n\n\n\nFinally\, I will demonstrate that properties can be measured with a time resolution limited only by the minimal energy (or force) detectable by AFM. We demonstrate this by mechanically detecting the intensity autocorrelation of a 100fs optical pulse and locally mapping the second order non-linear susceptibility c(2). This opens the door to future atomically resolved spatio-dynamic characterization of exciton generation and recombination sites or the identification of defects in 2D materials suitable for emission of entangled photons. \n\n\n\nReferences: \n\n\n\n[1] M. Cowie\, et al.\, Phys. Rev. Materials 6\, 104002 (2022)[2] M. Cowie\, et al.\, Phys. Rev. Lett. 132\, 256202 (2024)[3] M. Cowie\, et al.\, Proc. Natl. Acad. Sci. USA 121 (44) e2404456121 (2024)[4] Z. Schumacher et al.\, Proc. Natl. Acad. Sci. USA 117\, 19773 (2020)
URL:https://thomasyoungcentre.org/event/ucl-lcn-seminar-measuring-properties-of-single-defects-dopants-and-quantum-dots-with-nm-spatial-resolution-prof-peter-grutter-mcgill-university/
LOCATION:UCL Physics A1/3\, Physics Building\, Gower Street\, London\, WC1E 6BT\, United Kingdom
CATEGORIES:Main event
END:VEVENT
END:VCALENDAR