Characterization of III-V compound semiconductor heterostructures grown by metalorganic chemical vapor deposition
Kim, Jongryoul
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https://hdl.handle.net/2142/23767
Description
Title
Characterization of III-V compound semiconductor heterostructures grown by metalorganic chemical vapor deposition
Author(s)
Kim, Jongryoul
Issue Date
1991
Doctoral Committee Chair(s)
Wayman, C. Marvin
Department of Study
Engineering, Materials Science
Discipline
Engineering, Materials Science
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Materials Science
Language
eng
Abstract
III-V compound semiconductor materials have had much attention because of their application to high speed electronic and optoelectronic devices. For achieving these purposes, it is required to produce high quality samples with uniform layer thickness, no defects, and abrupt interfaces. For this metalorganic chemical vapor deposition (MOCVD) is one of the most important growth methods. In this study, transmission electron microscopy (TEM) was used for the characterization of epilayer structures grown by the MOCVD technique. High resolution electron microscopy (HREM), the two beam technique and the convergent beam technique (CBED) were used. Cross sectional, plan view and cleavage samples using the ion milling or chemical etching method were used for TEM sample preparation. Tetragonal distortion occurs in the strained layer superlattice (SLS). Misfit dislocations are found above a certain layer thickness (critical thickness) and the critical thickness is related to the total strain state in SLS. Composition measurements of In$\sb{\rm 1-x}$Ga$\sb{\rm x}$As in SLS using TEM has restrictions because of the misfit strain and the similarity of atomic scattering factors of Ga and In. But a low In concentration layer can be determined from the (002) dark field intensity ratio. The interface quality of heterostructures can be distinguished by 5 beam, 9 beam or more conditions at a (100) zone axis. Digital vector pattern recognition was found to be a powerful tool for quantization of interface quality.
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