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Eades, J.A. Christenson, Kurt Karl 2011-05-17T18:53:17Z 2011-05-17T18:53:17Z 10000-01-01 1989 The diffusion of zinc in GaAs is highly anomalous in that the diffusion coefficient (D) is proportional to the zinc concentration squared in marked contrast to Fick's law which predicts that D is concentration independent. D is also very sensitive to the ambient conditions during diffusion, particularly the arsenic overpressure and the presence of other doping species. Further, heavy zinc doping can increase the self diffusion rates for gallium and aluminum by 105 and is thus useful for selectively ,disordering GaAs/GaAlAs layer structures. The diffusion mechanisms involved are poorly understood, particularly the experimental finding that the column V sites (As, P and Sb) are not disordered. We believe that the anomalous nature can be explained by combining the theories of R. L. Longini (1962) on the effect of the hole density on the interstitial population and of K. Weiser (1962) on the effect of the charge state of an interstitial on the diffusion activation energy. To test our hypothesis, we have located the position of the zinc in the GaAs lattice with the ALCHEMI technique (Atom Location by CHanneling Enhanced Microanalysis) in a Transmission Electron Microscope (TEM). This required substantial enhancements to the x-ray microanalytic abilities of the TEM along with an improved understand of the nature of the illumination in the immersion lens of a TEM, all of which are discussed. Our results indicate that, within the experimental error, all of the zinc occupies the gallium sites which is consistent with our hypothesis. Further research involving TEM, synchrotron, diffusion and device studies are also suggested. Submitted by Carolyn Mead (cmead2@illinois.edu) on 2011-05-17T18:53:17Z No. of bitstreams: 1 1989_christenson.pdf: 7131135 bytes, checksum: 4e7258d0a2c555f9c4f3fbff1f384d2f (MD5) Made available in DSpace on 2011-05-17T18:53:17Z (GMT). No. of bitstreams: 1 1989_christenson.pdf: 7131135 bytes, checksum: 4e7258d0a2c555f9c4f3fbff1f384d2f (MD5) Previous issue date: 1989 Restriction data tranferred 2014-07-01T11:16:48-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: Thesis Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Carolyn Mead (cmead2@illinois.edu) on 2011-05-17T18:53:17Z Item is restricted indefinitely. Thesis U of I Only 3480212 http://hdl.handle.net/2142/23931 en 1989 Kurt Karl Christenson Diffusion of Zinc in Gallium Arsenide (GaAs) Diffusion Coefficient Fick's Law Zinc Doping Channeling Studies Channeling studies of the location of zinc in GaAs Dissertation / Thesis text Physics Physics University of Illinois at Urbana-Champaign Dissertation Ph.D.