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Title: Thermal transport in thin films measured by time-resolved, grazing incidence x-ray diffraction.

We use depth- and time-resolved x-ray diffraction to study thermal transport across single crystal Bi films grown on sapphire in order to determine the thermal conductivity of the film and the Kapitza conductance of the interface. Ultrafast Ti:sapphire laser pulses were used to heat the films; x-ray diffraction then measured the film's lattice expansion. Use of grazing incidence diffraction geometry provided depth sensitivity, as the x-ray angle of incidence was varied near the critical angle. The shift of the film's Bragg peak position with time was used to determine the film temperature averaged over an x-ray penetration depth that could be selected by choice of the angle of incidence. For films that were thick compared to the laser penetration depth, we observed a large temperature gradient at early times. In this case, measurements with the incident angle near or well above the critical angle were more sensitive to the film conductivity or Kapitza conductance, respectively. For thinner films, however, cooling was dominated by the Kapitza conductance at all accessible time scales.
Authors:
; ; ;  [1] ;  [2] ;  [2] ;  [2]
  1. (X-Ray Science Division)
  2. (
Publication Date:
OSTI Identifier:
1032003
Report Number(s):
ANL/XSD/JA-68341
Journal ID: 0021-8979; TRN: US1200181
DOE Contract Number:
DE-AC02-06CH11357
Resource Type:
Conference
Resource Relation:
Journal Name: J. Appl. Phys.; Journal Volume: 110; Journal Issue: 10 ; 2011; Conference: 11th International Conference on Surface X-Ray and Neutron Scattering; Jul. 13, 2010 - Jul. 17, 2010; Evanston, IL
Research Org:
Argonne National Laboratory (ANL)
Sponsoring Org:
SC; NSF
Country of Publication:
United States
Language:
ENGLISH
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; BRAGG CURVE; DIFFRACTION; GEOMETRY; INCIDENCE ANGLE; LASERS; MONOCRYSTALS; NEUTRONS; PENETRATION DEPTH; SAPPHIRE; SCATTERING; SENSITIVITY; TEMPERATURE GRADIENTS; THERMAL CONDUCTIVITY; THIN FILMS; TRANSPORT; X-RAY DIFFRACTION