Similarity of Stranski-Krastanow growth of Ge/Si and SiGe/Si (001)

Journal Article · Tue Jan 07 00:00:00 EST 2014 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4837975· OSTI ID:22271087

Norris, D. J.; Qiu, Y.; Walther, T. ^[1]; Dobbie, A.; Myronov, M. ^[2]

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1. Department of Electronic and Electrical Engineering, University of Sheffield, Mappin Building, Mappin Street, Sheffield S1 3JD (United Kingdom)
2. Department of Physics, University of Warwick, Coventry CV4 7A (United Kingdom)

This study investigates the onset of islanding (Stranski-Krastanow transition) in strained pure germanium (Ge) and dilute silicon-germanium (SiGe) alloy layers grown by chemical vapour deposition on Si(001) substrates. Integration of compositional profiles is compared to a novel method for quantification of X-ray maps acquired in cross-sectional scanning transmission electron microscopy, together with simulations of surface segregation of Ge. We show that Si{sub 1−x}Ge{sub x} alloys for germanium concentrations x ≤ 0.27 grow two-dimensionally and stay flat up to considerable layer thicknesses, while layers with concentrations in the range 0.28 < x ≤ 1 form islands after deposition of ∼3.0/x monolayers (=quarter unit cells in the diamond lattice, ML). The uncertainty in the amount of deposited material for pure Ge is ±(0.2–0.3) ML. Modelling shows that of the amount of germanium deposited, 0.7 ML segregate towards the free surface so that only ∼2.3/x ML are directly incorporated in the layer within a few nanometres, in good agreement with our measurements. For pure Ge (x = 1), this thickness is smaller than most values quoted in the literature, which we attribute to the high sensitivity of our method to fractional monolayer changes in the effective chemical width of such thin layers.

• OSTI ID: 22271087
• Journal Information: Journal of Applied Physics, Vol. 115, Issue 1; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
36 MATERIALS SCIENCE
CHEMICAL VAPOR DEPOSITION
COMPARATIVE EVALUATIONS
COMPUTERIZED SIMULATION
CONCENTRATION RATIO
FCC LATTICES
GERMANIUM
GERMANIUM ALLOYS
GERMANIUM SILICIDES
INTERFACES
LAYERS
SILICON
SILICON ALLOYS
STRAINS
SUBSTRATES
THICKNESS
THIN FILMS
TRANSMISSION ELECTRON MICROSCOPY
X RADIATION