####################################################
# Yen-Ru Lee <junolee@uiuc.edu>
# requesting 5 days, at minimum=4 days
# beamline 33ID, X-ray studies of the growth of Ag films on Ge(111) and Ge(110)
# instrument 33ID-E surface
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# top:/home/www/beamtime-requests/req00988.txt
# UNICAT Member Beam Time Request  #988
# Original UNICAT Member Beam Time Request  #956
# created Mon May 01 01:19:04 CDT 2006
####################################################

apsrun:
	2006-02

beamline:
	33ID

collaboration:
	Yes

collaborator_Hawoong:
	ON

contact:
	junolee@uiuc.edu

days:
	5

description:
	Preparing atomically uniform films on semiconductor substrate is a subject of considerable scientific and technological interest. However, it is not easy to achieve in practice. Smooth Ag film can be grown on Si(111), Ge(111) and GaAs(110) above a critical thickness of 6 atomic layers. Above the critical thickness the growth takes layer-by-layer. And below, the Ag forms islands with magic or preferred heights. These preferred or critical thickness have been attributed to quantum size effect. Electrons in the metal film are confined by the vacuum and substrate barriers, and the confinement leads to modifications of electronic structure and energy. The Ag on Ge system is interesting because of the way the growth mode changes with temperature and its superconducting properties. We would like to use surface x-ray diffraction from a synchrotron source to investigate the morphology evolve from an initial smooth film through various metastable states before reaching a state of a local equilibrium, and the coverage of different height Ag structure is related to the thickness-dependent surface energy. Because of the confinement of free electrons to a quantum well state, the surface energy might demonstrate beating oscillation with film coverage. The structure evolution of Ag films grown at 110k on Ge(111) or Ge(110) substrate would be obtained as they are annealed to higher temperatures. The morphology of the film will be examined by quenching the system back to growth temperature 110k at multiple points and scanning the x-ray reflectivity during the annealing process.

equipment_required:
	n/a

experiment:
	X-ray studies of the growth of Ag films on Ge(111) and Ge(110)

foreign_nationals:
	n/a

hazards:
	n/a

instrument:
	33ID-E surface

instrument_other:
	

minimumdays:
	4

name:
	Yen-Ru Lee

nonmembers:
	n/a

submit:
	Submit

unacceptable_dates:
	n/a

z34ID_change_undulator:
	no

z34ID_details:
	n/a

z34ID_parasitic:
	no


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