The Dynamical Transition to Step-Flow Growth During Homoepitaxy of GaAs (001)

AbstractThe evolution of surface morphology of molecular-beam-epitaxy-grown GaAs (001) has been studied by scanning tunneling microscope. Images show that in the early stages of deposition the morphology oscillates between one -with twodimensional nucleation and coalescing islands, i.e. flat terraces. After the initial oscillatory regime, the system evolves to a dynamical steady state. This state is characterized by a constant step density. As such, the growth mode can be called a generalized step flow. Comparison with RHEED shows that there is a direct correspondence between the surface step density and the RHEED specular intensity. An increase in step density results in a decrease in specular intensity. Additionally, further deposition beyond 120 monolayers (up to 1450 monolayers) display a slowly increasing surface roughness.

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Fabrication of two-dimensional Si/Ge nanowires and nanorings

MRS Proceedings ◽

10.1557/proc-794-t1.7 ◽

2003 ◽

Vol 794 ◽

Author(s):

Midori Kawamura ◽

Bert Voigtländer ◽

Neelima Paul ◽

Vasily Cherepanov

Keyword(s):

Scanning Tunneling Microscope ◽

Molecular Beam ◽

Atomic Layer ◽

Scanning Tunneling ◽

Two Dimensional ◽

Chemical Sensitivity ◽

Tunneling Microscope ◽

Step Flow ◽

Self Organized ◽

Step Flow Growth

ABSTRACTWe show that two-dimensional Si/Ge nanostructures with a thickness of a single atomic layer can be imaged with chemical sensitivity using a scanning tunneling microscope (STM). An atomic layer of Bi terminating the surface is used to distinguish between Si and Ge. This distinction between Si and Ge enabled us to fabricate two-dimensional Si/Ge nanostructures in a controlled way by self-organized growth. Si/Ge nanoring structures consisting of alternating Si and Ge rings having a width of ∼5 nm were grown around a Si core on a Si(111) substrate by molecular beam epitaxy (MBE). The thickness of the Si and Ge rings is only one atomic layer (0.3 nm). Alternating Si/Ge nanowires with a width of ∼3.5 nm and a thickness of 0.3 nm were also fabricated using alternating Si/Ge deposition in the step flow growth mode.

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Development of Anisotropic GaAs (001) Surface Morphology During Molecular Beam Epitaxial Growth

MRS Proceedings ◽

10.1557/proc-317-53 ◽

1993 ◽

Vol 317 ◽

Cited By ~ 4

Author(s):

Allan J. Pidduck ◽

G.W. Smith ◽

A.M. Keir ◽

C.R. Whitehouse

Keyword(s):

Molecular Beam Epitaxy ◽

Surface Morphology ◽

Molecular Beam ◽

Step Flow ◽

Molecular Beam Epitaxial ◽

Amplitude Increase ◽

Roughness Amplitude ◽

Step Density ◽

Molecular Beam Epitaxial Growth ◽

Step Flow Growth

ABSTRACTWe have studied the development of a microscopically ridged [110] Morphology during (001) GaAs Molecular beam epitaxy, as a function of layer thickness and growth temperature. The ridge slopes are consistent with the [110] separation required to incorporate a majority of adatoms by step-flow growth. Thus step-flow can be a dominant growth mode even on nominally on-axis (singular) substrates. With increasing epilayer thickness, the ridge slopes, and surface step density, remain approximately constant, while the ridge spacings, and therefore roughness amplitude, increase steadily.

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