Nucleation mechanisms and the elimination of misfit dislocations at mismatched interfaces by reduction in growth area

Journal Article · Wed Mar 15 04:00:00 EST 1989 · J. Appl. Phys.; (United States)

DOI:https://doi.org/10.1063/1.342834· OSTI ID:6479760

Fitzgerald, E A; Watson, G P; Proano, R E; Ast, D G; Kirchner, P D; Pettit, G D; Woodall, J M

To investigate the effect of growth area on interface dislocation density in strained-layer epitaxy, we have fabricated 2-..mu..m-high mesas of varying lateral dimensions and geometry in (001) GaAs substrates with dislocation densities of 1.5 x 10/sup 5/, 10/sup 4/, and 10/sup 2/ cm/sup -2/. 3500-, 7000-, and 8250-A-thick In/sub 0.05/Ga/sub 0.95/As layers, corresponding to 5, 10, and 11 times the experimental critical layer thickness as measured for large-area samples, were then deposited by molecular-beam epitaxy. For the 3500-A layers, the linear interface dislocation density, defined as the inverse of the average dislocation spacing, was reduced from greater than 5000 to less than 800 cm/sup -1/ for mesas as large as 100 ..mu..m. A pronounced difference in the linear interface dislocation densities along the two interface <110> directions indicates that ..cap alpha.. dislocations nucleate about twice as much as ..beta.. dislocations. For samples grown on the highest dislocation density substrates, the linear interface-dislocation density was found to vary linearly with mesa width and to extrapolate to a zero linear interface-dislocation density for a mesa width of zero. This behavior excludes dislocation multiplication or the nucleation of surface half-loops as operative nucleation sources for misfit dislocations in these layers. Only nucleation sources that scale with area (termed fixed sources) are active. In specimens with lower substrate dislocation densities, the density of interface dislocations still varies linearly with mesa size, but the slope becomes independent of substrate dislocation density, indicating that surface inhomogeneities now act as the dominant source for misfit dislocations.

• Research Organization: Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853
• OSTI ID: 6479760
• Journal Information: J. Appl. Phys.; (United States), Journal Name: J. Appl. Phys.; (United States) Vol. 65:6; ISSN JAPIA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360602* -- Other Materials-- Structure &amp; Phase Studies
ARSENIC COMPOUNDS
ARSENIDES
CHEMICAL COMPOSITION
COATINGS
CRYSTAL DEFECTS
CRYSTAL FACES
CRYSTAL GROWTH
CRYSTAL STRUCTURE
DATA
DISLOCATIONS
ELASTIC SCATTERING
ELECTRON MICROSCOPY
EPITAXY
EXPERIMENTAL DATA
FILMS
GALLIUM ARSENIDES
GALLIUM COMPOUNDS
INDIUM ARSENIDES
INDIUM COMPOUNDS
INFORMATION
INTERFACES
LINE DEFECTS
MICROSCOPY
MOLECULAR BEAM EPITAXY
NUMERICAL DATA
PNICTIDES
RUTHERFORD SCATTERING
SCANNING ELECTRON MICROSCOPY
SCATTERING
SPECTROSCOPY
SUBSTRATES
SURFACE PROPERTIES
THIN FILMS
X-RAY SPECTROSCOPY