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BEGIN:VEVENT
DTSTAMP:20261020T001710Z
LAST-MODIFIED:20171204T215759Z
DTSTART:20171206T133000Z
DTEND:20171206T140000Z
UID:event1860@bu.edu
URL:http://physics.bu.edu/internal/events/show/1860
SUMMARY:RIVETING TWO-DIMENSIONAL MATERIALS: EXPLORING STRAIN PHYSICS IN ATO
	MICALLY THIN CRYSTALS WITH MICROELECTROMECHANICAL SYSTEMS
DESCRIPTION:Featuring Jason Christopher\, Boston University\, Department of
	 Physics\n\nPart of the PhD Final Oral Exams.\n\nABSTRACT\nTwo dimensional 
	(2D) materials can withstand an order of magnitude more strain than their b
	ulk counterparts\, which results in dramatic changes to electrical\, therma
	l and optical properties.  These changes can be harnessed for technological
	 applications such as tunable light emitting diodes or field effect transis
	tors\, or utilized to explore novel physics like exciton confinement\, pseu
	do-magnetic fields (PMFs)\, and even quantum gravity.  However\, current te
	chniques for straining atomically thin materials offer limited control over
	 the strain field\, and require bulky pressure chambers or large beam bendi
	ng equipment. This dissertation describes the development of micro-electrom
	echanical systems (MEMS) as a platform for precisely controlling the magnit
	ude and orientation of the strain field in 2D materials.  MEMS are a versat
	ile platform for studying strain physics. Mechanical\, electrical\, thermal
	 and optical probes can all be easily incorporated into their design.  Furt
	her\, because of their small size and compatibility with electronics manufa
	cturing methods\, there is an achievable pathway from the laboratory bench 
	to real-world application.  Nevertheless\, the incorporation of atomically 
	thin crystals with MEMS has been hampered by fragile\, non-planer structure
	s and low friction interfaces.  We have innovated two techniques to overcom
	e these critical obstacles: micro-structure assisted transfer to place the 
	2D materials on the MEMS gently and precisely\, and micro-riveting to creat
	e a slip-free interface between the 2D materials and MEMS. With these advan
	cements\, we were able to strain monolayer molybdenum disulfide (MoS2) to g
	reater than 1% strain with a MEMS for the first time.  The dissertation dev
	elops the theoretical underpinnings of this result including original work 
	on the theory of operation of MEMS chevron actuators\, and strain generated
	 PMFs in transition metal dichalcogenides\, a large class of 2D materials. 
	 We conclude the dissertation with a roadmap to guide and inspire future ph
	ysicists and engineers exploring strain in 2D systems and their application
	s.  The roadmap contains ideas for next-generation fabrication techniques t
	o improve yield\, sample quality\, and add capabilities.  We have also incl
	uded in the roadmap proposals for experiments such as a speculative techniq
	ue for realizing topological quantum field theories that mimics recent theo
	retical wire construction methods.\n\n![Jason](/resources/event-image/1860/
	c555177_small)
LOCATION:SCI 352\, 590 Commonwealth Avenue\, 02215
STATUS:CONFIRMED
CLASS:PUBLIC
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