Structural Analysis of Highly Relaxed GaSb Grown on GaAs Substrates with Periodic Interfacial Array of 90° Misfit Dislocations |
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Authors: | A Jallipalli G Balakrishnan S H Huang T J Rotter K Nunna B L Liang L R Dawson D L Huffaker |
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Affiliation: | (1) Electrical Engineering Department, University of California at Los Angeles, Los Angeles, CA 90095, USA;(2) Center for High Technology Materials, University of New Mexico, Albuquerque, NM 87106, USA;(3) Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, NM 87131, USA;(4) California NanoSystems Institute, University of California at Los Angeles, Los Angeles, CA 90095, USA |
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Abstract: | We report structural analysis of completely relaxed GaSb epitaxial layers deposited monolithically on GaAs substrates using
interfacial misfit (IMF) array growth mode. Unlike the traditional tetragonal distortion approach, strain due to the lattice
mismatch is spontaneously relieved at the heterointerface in this growth. The complete and instantaneous strain relief at
the GaSb/GaAs interface is achieved by the formation of a two-dimensional Lomer dislocation network comprising of pure-edge
(90°) dislocations along both 110] and 1-10]. In the present analysis, structural properties of GaSb deposited using both
IMF and non-IMF growths are compared. Moiré fringe patterns along with X-ray diffraction measure the long-range uniformity
and strain relaxation of the IMF samples. The proof for the existence of the IMF array and low threading dislocation density
is provided with the help of transmission electron micrographs for the GaSb epitaxial layer. Our results indicate that the
IMF-grown GaSb is completely (98.5%) relaxed with very low density of threading dislocations (105 cm−2), while GaSb deposited using non-IMF growth is compressively strained and has a higher average density of threading dislocations
(>109 cm−2). |
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Keywords: | Semiconductor GaSb/GaAs Molecular beam epitaxy Interfacial misfit dislocations (IMF) or Lomer dislocations Strain relief Structural properties Moiré fringes |
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