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Title: Study of the Defect Eliminations Mechanisms in Aspect Ratio Trapping Ge Growth

Abstract

Recent research has demonstrated the effectiveness of the 'aspect ratio trapping' technique for eliminating threading dislocations in Ge grown selectively in submicron trenches on Si substrates. In this letter, analysis of the mechanisms by which dislocation elimination is achieved has been carried out. Detailed transmission electron microscopy studies reveal that facets, when formed early in the growth process, play a dominant role in determining the configurations of threading dislocations in the films. These dislocations are shown to behave as 'growth dislocations', which are replicated during growth approximately along the facet normal and so are deflected out from the center of the selective epitaxial regions.

Authors:
; ; ; ; ; ; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
930554
Report Number(s):
BNL-80677-2008-JA
Journal ID: ISSN 0003-6951; APPLAB; TRN: US200904%%586
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 90; Journal Issue: 10
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; GERMANIUM; CRYSTAL GROWTH; DISLOCATIONS; SUBSTRATES; SILICON; MITIGATION; national synchrotron light source

Citation Formats

Bai,J., Park, J., Cheng, Z., Curtin, M., Adekore, B., Carroll, M., Lochtefeld, A., and Dudley, M.. Study of the Defect Eliminations Mechanisms in Aspect Ratio Trapping Ge Growth. United States: N. p., 2007. Web. doi:10.1063/1.2711276.
Bai,J., Park, J., Cheng, Z., Curtin, M., Adekore, B., Carroll, M., Lochtefeld, A., & Dudley, M.. Study of the Defect Eliminations Mechanisms in Aspect Ratio Trapping Ge Growth. United States. doi:10.1063/1.2711276.
Bai,J., Park, J., Cheng, Z., Curtin, M., Adekore, B., Carroll, M., Lochtefeld, A., and Dudley, M.. Mon . "Study of the Defect Eliminations Mechanisms in Aspect Ratio Trapping Ge Growth". United States. doi:10.1063/1.2711276.
@article{osti_930554,
title = {Study of the Defect Eliminations Mechanisms in Aspect Ratio Trapping Ge Growth},
author = {Bai,J. and Park, J. and Cheng, Z. and Curtin, M. and Adekore, B. and Carroll, M. and Lochtefeld, A. and Dudley, M.},
abstractNote = {Recent research has demonstrated the effectiveness of the 'aspect ratio trapping' technique for eliminating threading dislocations in Ge grown selectively in submicron trenches on Si substrates. In this letter, analysis of the mechanisms by which dislocation elimination is achieved has been carried out. Detailed transmission electron microscopy studies reveal that facets, when formed early in the growth process, play a dominant role in determining the configurations of threading dislocations in the films. These dislocations are shown to behave as 'growth dislocations', which are replicated during growth approximately along the facet normal and so are deflected out from the center of the selective epitaxial regions.},
doi = {10.1063/1.2711276},
journal = {Applied Physics Letters},
number = 10,
volume = 90,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • The Aspect Ratio Trapping technique has been extensively evaluated for improving the quality of III-V heteroepitaxial films grown on Si, due to the potential for terminating defects at the sidewalls of SiO{sub 2} patterned trenches that enclose the growth region. However, defects propagating along the trench direction cannot be effectively confined with this technique. We studied the effect of the trench bottom geometry on the density of defects of GaAs fins, grown by metal-organic chemical vapor deposition on 300 mm Si (001) wafers inside narrow (<90 nm wide) trenches. Plan view and cross sectional Scanning Electron Microscopy and Transmission Electron Microscopy, togethermore » with High Resolution X-Ray Diffraction, were used to evaluate the crystal quality of GaAs. The prevalent defects that reach the top surface of GaAs fins are (111) twin planes propagating along the trench direction. The lowest density of twin planes, ∼8 × 10{sup 8 }cm{sup −2}, was achieved on “V” shaped bottom trenches, where GaAs nucleation occurs only on (111) Si planes, minimizing the interfacial energy and preventing the formation of antiphase boundaries.« less
  • We report experiments on convection patterns in a cylindrical cell with a large aspect ratio. The fluid had a Prandtl number [sigma][approx]1. We observed a chaotic pattern consisting of many rotating spirals and other defects in the parameter range where theory predicts that steady straight rolls should be stable. The correlation length of the pattern decreased rapidly with increasing control parameter so that the size of a correlated area became much smaller than the area of the cell. This suggests that the chaotic behavior is intrinsic to large aspect ratio geometries.
  • Electronic structures of (4, n) and (m, 4) (the NW has m layers parallel to the {1 1 1} facet and n layers parallel to {1 1 0}) Si/Ge core/shell nanowires (NWs) along the [1 1 2] direction with cross-sectional aspect ratio (m/n) from 0.36 to 2.25 are studied by first-principles calculations. An indirect to direct band gap transition is observed as m/n decreases, and the critical values of m/n and diameter for the transition are also estimated. The size of the band gap also depends on the aspect ratio. These results suggest that m/n plays an important role inmore » modulating the electronic properties of the NWs.« less
  • Homoepitaxial selective growth of a GaAs nanoscale, high-aspect ratio, one-dimensional (1D) grating with vertical facets is reported. For a pattern direction along [110], the kinetics of faceting in selective molecular-beam epitaxy (MBE) induce (110)-type facets vertical to a GaAs(001) substrate near the boundary between an SiO{sub 2} mask and an open substrate area. On a 1.25-{mu}m period, 1D stripe, SiO{sub 2}-patterned GaAs(001) substrate with an opening width of {approx}300 nm, vertical faceting results in a grating structure consisting of 2.8-{mu}m-high, 820-nm-wide features. Kinetics of faceting in selective MBE is explained as a result of the minimization of total surface energy.
  • The epitaxial growth of quantum rods (QRs) on GaAs was investigated. It was found that GaAs thickness in the GaAs/InAs superlattice used for QR formation plays a key role in improving the QR structural properties. Increasing the GaAs thickness results in both an increased In compositional contrast between the QRs and surrounding layer, and an increased QR length. QRs with an aspect ratio of up to 10 were obtained, representing quasiquantum wires in a GaAs matrix. Due to modified confinement and strain potential, such nanostructure is promising for controlling gain polarization.