Epitaxial (GaAs)[sub 1[minus]][sub [ital x]](Si[sub 2])[sub [ital x]] metastable alloys on GaAs(001) and (GaAs)[sub 1[minus]][sub [ital x]](Si[sub 2])[sub [ital x]] /GaAs strained-layer superlattices: Crystal growth, spinodal decomposition, and antiphase domains

Journal Article · Mon Aug 01 04:00:00 EDT 1994 · Journal of Applied Physics; (United States)

DOI:https://doi.org/10.1063/1.357749· OSTI ID:7028204

Kim, Y; Mei, D H; Lubben, D; Robertson, I; Greene, J E ^[1]

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1. Department of Materials Science, Coordinated Science Laboratory, and Materials Research Laboratory, University of Illinois, 1101 West Springfield Avenue, Urbana, Illinois 61801 (United States)

The microstructure of single-crystal zincblende-structure (GaAs)[sub 1[minus][ital x]](Si[sub 2])[sub [ital x]] metastable semiconducting alloys with 0[le][ital x][le]0.40 has been investigated using triple-crystal x-ray diffraction (XRD), plan-view and cross-sectional transmission electron microscopy (TEM and XTEM), scanning transmission electron microscopy, and convergent-beam electron diffraction. The alloys, typically 1--3 [mu]m thick, were grown using a hybrid sputter-deposition/evaporation technique on As-stabilized GaAs(001) and (GaAs)[sub 1[minus][ital x]](Si[sub 2])[sub [ital x]]/GaAs(001) strained-layer superlattices, (SLS). Alloy XRD peak widths were approximately equal to those of the GaAs substrates, 30 arcsec, and lattice constants, uncorrected for strain, obeyed Vegard's law'' and decreased linearly with increasing [ital x]. TEM and XTEM examinations of (GaAs)[sub 1[minus][ital x]](Si[sub 2])[sub [ital x]] alloys with 0[le][ital x][le]0.20 grown on GaAs revealed no evidence of dislocations or other extended defects. Film/substrate lattice misfit strain in alloys with 0.11[lt][ital x][lt]0.20 was partially accommodated by the formation of a thin interfacial spinodal layer whose average thickness increased with [ital x] to [congruent]70 nm. The spinodal region, which remained epitaxial, consisted of lenticular platelets extending along the [001] direction with a compositional modulation in orthogonal directions. Films with [ital x][ge]0.20 exhibited, together with the interfacial zones, inhomogeneously distributed [ital a][sub 0]/2[l angle]110[r angle]-type threading dislocations. Antiphase domains were observed in alloys with [ital x][ge]0.23. The use of (GaAs)[sub 1[minus][ital x]](Si[sub 2])[sub [ital x]]/GaAs SLS buffer layers extended the composition range to [ital x]=0.3 over which dislocation-free alloys, with no evidence of interfacial spinodal decomposition, could be obtained.

• DOE Contract Number: AC02-76ER01198
• OSTI ID: 7028204
• Journal Information: Journal of Applied Physics; (United States), Journal Name: Journal of Applied Physics; (United States) Vol. 76:3; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360606* -- Other Materials-- Physical Properties-- (1992-)
ALLOYS
ARSENIC COMPOUNDS
ARSENIDES
COHERENT SCATTERING
CRYSTAL DEFECTS
CRYSTAL GROWTH
CRYSTAL STRUCTURE
DIFFRACTION
DISLOCATIONS
DOMAIN STRUCTURE
ELECTRON DIFFRACTION
ELECTRON MICROSCOPY
GALLIUM ARSENIDES
GALLIUM COMPOUNDS
LINE DEFECTS
MICROSCOPY
MICROSTRUCTURE
PNICTIDES
SCATTERING
SILICON ALLOYS
STRAINS
SUPERLATTICES
X-RAY DIFFRACTION