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Holonyak, Nick, Jr. Guido, Louis Joseph 2011-05-07T14:06:03Z 2011-05-07T14:06:03Z 10000-01-01 1989 In the experiments described here, Al$\sb{\rm x}$Ga$\sb{\rm 1-x}$As-GaAs superlattice and quantum well heterostructure (QWH) crystals have been used as test vehicles to study Al-Ga interdiffusion. The data demonstrate that Al-Ga interchange is strongly influenced by the interdependence of the crystal surface-ambient interaction and the Fermi-level effect. We have investigated the crystal surface-ambient interaction by varying both the surface encapsulation condition (e.g., SiO$\sb2$-cap, Si$\sb3$N$\sb4$-cap) and the anneal ambient (As-rich, Ga-rich). The Fermi-level effect has been examined for QWH crystals doped with either donor or acceptor impurities during crystal growth and annealed, and for crystals converted to n-type conductivity by high-temperature Si diffusion or by Si$\sp+$ ion implantation and annealing. The data show that Al-Ga interchange is enhanced for n-type samples annealed under As-rich conditions, and for p-type samples annealed under Ga-rich conditions. These trends suggest that acceptor native defects (V$\sb{\rm III}$) and donor native defects (I$\sb{\rm III}$, V$\sb{\rm As}$) are responsible for Al-Ga interdiffusion in n-type and p-type samples, respectively. By varying the anneal As$\sb4$ over-pressure we have demonstrated that the degree of Al-Ga interchange does not increase monotonically for n-type samples as expected for a simple Column III vacancy controlled process. In addition, we show that the activation energy for Al-Ga interdiffusion (E$\sb{\rm Al-Ga}$) is reduced by $\sb\sim$2 eV for n-type samples as compared to nominally undoped samples. These results indicate that E$\sb{\rm Al-Ga}$ can be used to label the various Al-Ga interdiffusion regimes and, thereby, provide for more accurate identification of the native defect species involved in the interchange process. Furthermore, by employing three single-well QWH crystals that differ only in the location of the QW relative to the crystal surface, we demonstrate that the Al-Ga interchange mechanism is depth-dependent because of the re-equilibration of native defect concentrations at the crystal free surface. Finally, we report on Si$\sp+$ ion implantation experiments that demonstrate enhanced Si$\sp+$-IILD for very low implant doses, hence minimizing the effects of implant damage. Made available in DSpace on 2011-05-07T14:06:03Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 8916256.pdf: 2301924 bytes, checksum: a49eb1c268c04eb612ad8c0537a0751f (MD5) Previous issue date: 1989 Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T15:02:55Z Item is restricted indefinitely. Restriction data tranferred 2014-07-01T11:29:57-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: ETDs are only available to UIUC Users without author permission ETDs are only available to UIUC Users without author permission U of I Only AAI8916256 (UMI)AAI8916256 http://hdl.handle.net/2142/23209 eng Copyright 1989 Guido, Louis Joseph Engineering, Electronics and Electrical Layer disordering and aluminum-gallium interchange in aluminum-gallium arsenide - gallium-arsenide quantum well heterostructures text Electrical and Computer Engineering Electrical and Computer Engineering University of Illinois at Urbana-Champaign Dissertation Ph.D.