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SUMMARY:Scanning probe microscopy of GaN: Beyond pretty pictures - Rachel 
 Oliver\, Department of Materials Science and Metallurgy\, University of Ca
 mbridge
DTSTART:20061024T140000Z
DTEND:20061024T150000Z
UID:TALK5764@talks.cam.ac.uk
CONTACT:Edmund Ward
DESCRIPTION:Scanning probe microscopy (SPM) techniques\, principally atomi
 c force microscopy (AFM)\, provide a relatively simple\, fast-turnaround w
 ay to assess the surface morphology of many materials. Interesting and att
 ractive images are frequently obtained. However\, AFM sometimes seem to be
  a victim of its own success and simplicity\, with morphological data bein
 g published with little by way of analysis or interpretation.\n\nIn the Ca
 mbridge GaN centre\, various attempts have been made to take the use of SP
 M beyond this "pretty pictures" level. I will describe two examples of the
  use of topographical AFM data and its analysis in this context: (1) the d
 evelopment of a surface treatment which allows straightforward imaging of 
 threading dislocations at GaN surfaces\, and its application in a study of
  the origins of threading dislocations\, and (2) the application of spectr
 al analysis of AFM images to understanding the mechanisms of roughening an
 d smoothing in InGaN films during annealing.\n\nCurrently available SPM te
 chniques\, however\, extend the capability of the instrument far beyond th
 e topographic realm. As examples of these more recently developed techniqu
 es\, I will present: (1) the use of scanning capacitance microscopy for th
 e quantification of carrier concentrations in n-type GaN and (2) the devel
 opment of scanning spreading resistance microscopy as a composition-sensit
 ive tool for the imaging of AlGaN samples.\n\nTogether\, these four case s
 tudies may illustrate the broad applicability of SPM to understanding the 
 structure and properties of materials.
LOCATION:T001 [Tower Seminar Room]\, Materials Science and Metallurgy\, De
 partment of
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