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Coherent Carrier Transport through 2D PbS Quantum Dots

Date: 2019-05-28
Time: 14:00
Venue: M253
Speaker: Dr. Yuanxun Liao

University of Manchester, United Kingdom 


Coherent electron transports have been observed through a monolayer of 4nm PbS quantum dots (QD) of short-range orders.  Coherent injection from Si leads to multi-dot resonant tunneling.  The resonant tunneling shows ideal negative differential resistance (NDR), due to inter-dot coherence.  The needle-like NDRs have peak-to-valley-current ratios above 800 and line-widths below several meV.  This is attributed to the size distribution of QDs and the short-range delocalization when variable-range-hopping changing to nearest-neighbor-hopping.  The ultra-high quality NDR once only achieved by gate-defined QDs at near-zero temperature now could be possible with macroscale 2D colloidal QDs at room-temperature.  This amazing fact inspires a ‘laser-like’ solid electron source, which could be very useful for quantum electronics and quantum information.  These findings enrich our understandings for carrier transport in QDs and expand QD applications.

Brief CV of Dr. Yuanxun Liao: 

Dr Yuanxun Liao is currently a postdoc in the National Graphene Institute of University of Manchester of UK. He is working in the group of Prof. Sir Kostya Novoselov, the 2010 Physics Nobel Prize winner, on 2D magnetic materials. He got his PhD on photovoltaics engineering from the School of Photovoltaics and Renewable Energy of University of New South Wales of Australia in 2014. During his PhD, he worked on hot carrier solar cells and first achieved resonant tunnelling though quantum dots at room temperature. Besides, he got his Master in Optics from Institute of Higher Energy Physics of CAS in 2009.