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Details of Grant 

EPSRC Reference: GR/M85371/01
Title: PROFILING PIEZOELECTRIC FIELDS IN GAN/ALN/INN STRUCTURES BY ELECTRON HOLOGRAPHY
Principal Investigator: Cherns, Professor D
Other Investigators:
Researcher Co-Investigators:
Project Partners:
Department: Physics
Organisation: University of Bristol
Scheme: Standard Research (Pre-FEC)
Starts: 01 January 2000 Ends: 31 May 2003 Value (£): 151,891
EPSRC Research Topic Classifications:
Materials Characterisation
EPSRC Industrial Sector Classifications:
Electronics No relevance to Underpinning Sectors
Related Grants:
Panel History:  
Summary on Grant Application Form
The performance of GaN devices is influenced by piezoelectric fields associated with strained layers, fields due to spontaneous polarisation around planar defects and fields due to charging of threading dislocations. The aim of this project is to develop an electron holographic method to profile these fields building on our preliminary work in this area. We aim to develop our profiling of piezoelectric fields in cross-sectional (0001) GaN/InGaN layers by accounting quantitatively for diffraction contrast effects due to surface relaxation of misfit strains. This should allow layers to be examined edge-on, enabling fields around layer irregularities (quantum dots) to be examined. These studies will be extended to AlGaN/GaN layers. The techniques will then be extended to examine firstly the changes in piezoelectric fields expected around misfit dislocations, and then the fields expected around threading dislocations due to charging. Exploratory experiments will also be carried out to examine the Fresnel contrast, in large angle convergent beam electron diffraction patterns, from strained layers and planar defects, which contains further information on local fields.
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Organisation Website: http://www.bris.ac.uk