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VERSION:2.0
PRODID:-//RLASKEY//CALENDEROUS//EN
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METHOD:PUBLISH
BEGIN:VEVENT
DTSTAMP:20261020T025330Z
LAST-MODIFIED:20180130T155625Z
DTSTART:20180207T160000Z
DTEND:20180207T170000Z
UID:event1911@bu.edu
URL:http://physics.bu.edu/internal/events/show/1911
SUMMARY: Nano-Patterning by Ion Bombardment
DESCRIPTION:Featuring Mahsa Mokhtarzadeh\n\nPart of the Departmental Semina
	rs.\n\nExamining Committee: Karl Ludwig\, Ophelia Tsui\, Anatoli Polkovniko
	v\, Lee Roberts\n\nAbstract:\n\n The bombardment of surfaces by ions can le
	ad to the spontaneous formation of nano-structures. Depending on the irradi
	ation conditions\, smoothening or roughening mechanisms can be the leading 
	order in pattern formation which can result in the creation of dots\, rippl
	es or ultra-smoothening effects. The fundamental processes governing surfac
	e pattern formation are not well understood; therefore\, understanding the 
	physical mechanisms of surface evolution during ion bombardment is one of o
	ur research goals. Our recent grazing incidence small angle x-ray scatterin
	g (GISAXS) measurements of the structure factor of Si surfaces undergoing 1
	 keV Ar+ ion-bombardment indicate an important role for ion-induced stress 
	as a competing mechanism along with the more recognized impact-induced redi
	stribution and erosion processes for pattern formation. Therefore\, stress 
	measurement techniques were also designed and performed in our lab in order
	 to measure the stress in Si surfaces irradiated as a function of ion energ
	y\, flux and angle. Moreover\, using new x-ray photon correlation spectrosc
	opy (XPCS) techniques in a coherent GISAXS scattering geometry offers exten
	sive new opportunities to investigate surface dynamical processes and fluct
	uations in much greater detail than was previously possible. We have taken 
	advantage of this new capability to perform XPCS studies of SiO2 surfaces u
	nder various ion-beam irradiation conditions. The early time as well as the
	 steady state regime of the surface evolution provide us valuable informati
	on that can lead to better understanding the mechanisms of pattern formatio
	n. In addition\, I will present the results of simulations of growth models
	 such as linear Kuramoto- Sivashinsky (KS) and Kardar-Parisi-Zhang (KPZ) th
	at have been carried out for comparing the temporal correlation functions o
	f the scattered intensity with the new Co-GISAXS experiments.
LOCATION:SCI 352\, 590 Commonwealth Avenue\, 02215
STATUS:CONFIRMED
CLASS:PUBLIC
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