Investigation of implantation damage in aluminum gallium arsenide/gallium arsenide heterostructures using ion channeling and transmission electron microscopy
Turkot, Britt Anne
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https://hdl.handle.net/2142/20847
Description
Title
Investigation of implantation damage in aluminum gallium arsenide/gallium arsenide heterostructures using ion channeling and transmission electron microscopy
Author(s)
Turkot, Britt Anne
Issue Date
1996
Doctoral Committee Chair(s)
Robertson, Ian M.
Department of Study
Materials Science and Engineering
Discipline
Materials Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Electronics and Electrical
Engineering, Materials Science
Language
eng
Abstract
The implantation damage behavior of GaAs/Al$\sb{0.6}$Ga$\sb{0.4}$As multilayer structures has been investigated by implanting samples with 1 MeV Kr$\sp+$, 1.5 MeV Kr$\sp+$, 1 MeV Ar$\sp+$, and 1.5 MeV Kr$\sp{++}$ at 77 K. The resulting damage state was analyzed using low-, room-, and high-temperature Rutherford backscattering spectrometry ion channeling and room-temperature transmission electron microscopy techniques. In all implantations the level of damage produced in these structures was found to increase with depth, and the damage state produced in samples containing single- and double-layers of $\rm Al\sb{0.6}Ga\sb{0.4}As$ was independent of the internal interfaces. The observed damage can be explained using a model which relates the amount of implantation-induced disorder to the number of cascade-producing events in a given region. This model can also account for results in the GaAs/AlAs system, such as the greater amount of mixing which is observed to occur at deeper AlAs interfaces and also that amorphization of AlAs layers initiates at the interfaces.
Room temperature recovery of partially crystalline $\rm Al\sb{0.6}Ga\sb{0.4}As$ was observed to occur following low temperature implantation. Depending on the implantation condition, this room temperature recovery can lead to the development of planar defects. In addition, the extent of recovery in $\rm Al\sb{0.6}Ga\sb{0.4}As$ was found to be related to the original damage state, with more complex damage requiring higher annealing temperatures.
Misoriented crystallites were produced by the recrystallization of GaAs implanted at room temperature to a dose far exceeding that required for low temperature amorphization. Continued ion impacts produced crystalline nucler which increased in size as a result of the enhanced atomic motion produced by the energetic ions. Similar crystallites were found in TEM foils which remained in the as-thinned condition for several months. In these samples, recrystallization resulted from a mechanism involving low energy events with the ability to induce bond rearrangement.
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