Continuum model of surface roughening and epitaxial breakdown during low-temperature Ge(001) molecular beam epitaxy

Journal Article · Tue Mar 15 04:00:00 EDT 2011 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.3556745· OSTI ID:21538167

Bratland, K A; Spila, T; Cahill, D G; Greene, J E ^[1]; Desjardins, P ^[2]

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1. Frederick Seitz Materials Research Laboratory and the Materials Science and Engineering Department, University of Illinois, 104 South Goodwin Avenue, Urbana, Illinois 61801 (United States)
2. Regroupement quebecois sur les materiaux de pointe and Departement de genie physique, Ecole Polytechnique de Montreal, P.O. Box 6079, Station Centre-Ville, Montreal, Quebec H3C 3A7 (Canada)

Numerical simulations based on a discrete model describing step edge motion are used to compute the surface morphological evolution of Ge(001) layers deposited by low-temperature (T{sub s} = 45-230 deg. C) molecular beam epitaxy and to probe the relationship between surface roughening and the onset of epitaxial breakdown - the abrupt growth mode transition from epitaxial to amorphous - at temperature-dependent critical film thicknesses h{sub 1}(T{sub s}). Computed surface widths w and in-plane coherence lengths d as a function of layer thickness h exhibit good agreement with experimental values. Inspired by experimental results indicating that epitaxial breakdown is initiated at facetted interisland trenches as the surface roughness reaches a T{sub s}-independent overall aspect ratio, we show that simulated data for w/d = 0.03 correspond to thicknesses h{sub 1{proportional_to}} exp (-E{sub 1}/kT{sub s}) with E{sub 1} = 0.63 eV, a value equal to the Ge adatom diffusion activation energy on Ge(001). Simulated h{sub 1} values agree well with experimental data. Above a critical growth temperature of 170 deg. C, computed w/d values saturate at large film thicknesses, never reaching the critical aspect ratio w/d = 0.03. Thus, the model also predicts that epitaxial breakdown does not occur for T{sub s} > 170 deg. C as observed experimentally.

• OSTI ID: 21538167
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 6 Vol. 109; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ACTIVATION ENERGY
ANIMAL CELLS
ASPECT RATIO
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
BODY FLUIDS
BREAKDOWN
COHERENCE LENGTH
COMPUTERIZED SIMULATION
CONNECTIVE TISSUE CELLS
CRYSTAL GROWTH METHODS
DIFFUSION
DIMENSIONLESS NUMBERS
DIMENSIONS
ELEMENTS
ENERGY
ENERGY RANGE
EPITAXY
EV RANGE
FILMS
GERMANIUM
GROWTH FACTORS
INTERFERON
LENGTH
LEUKOCYTES
LYMPHOCYTES
LYMPHOKINES
MATERIALS
MEMBRANE PROTEINS
METALS
MITOGENS
MOLECULAR BEAM EPITAXY
ORGANIC COMPOUNDS
PROTEINS
ROUGHNESS
SIMULATION
SOMATIC CELLS
SURFACE PROPERTIES
SURFACES
TEMPERATURE DEPENDENCE
THICKNESS