Unstable Growth and Coarsening in Molecular-Beam Epitaxy
نویسنده
چکیده
The coarsening dynamics of three-dimensional islands on a growing film is discussed. It is assumed that the origin of the initial instability of a planar surface is the Ehrlich-Schwoebel step-edge barrier for adatom diffusion. Two mechanisms of coarsening are identified: (i) surface diffusion driven by an uneven distribution of bonding energies, and (ii) mound coalescence driven by random deposition. Semiquantitative estimates of the coarsening time are given in each case. When the surface slope saturates, an asymptotic dynamical exponent z = 4 is obtained.
منابع مشابه
Wavelet analysis of coarsening during unstable MBE growth
We present a wavelet analysis of coarsening of mounds during molecular beam epitaxy. The advantage in using wavelets over Fourier analysis is that one can track the coarsening process in both, location (direct space) and frequency (or scale) space at the same time. The wavelets concise scale decomposition allows the discrimination of the coarsening process, i.e. tracking coarsening at different...
متن کاملNanoscale Phase Separation in Fe,O,(lll) Films on Sapphire(OOO1) and Phase Stability of Fe,O,(OOl) Films on MgO(001) Grown by Oxygen-Plasma-Assisted Molecular Beam Expitaxy
Nanoscale phase separation in Fe304(l 11) films on sapphire(0001) and phase stability of Fe304(001) films on MgO(001) grown by oxygen-plasma-assisted molecular beam epitaxy We report a phase instability in oxygen-plasma-assisted molecular beam epitaxy of Fe304 films on sapphire (0001) substrates. Under a wide range of growth conditions, Fe304 (111) films phase separate, on a nanometer length sc...
متن کاملCoarsening of Surface Structures in Unstable Epitaxial Growth
We study unstable epitaxy on singular surfaces using continuum equations with a prescribed slope-dependent surface current. We derive scaling relations for the late stage of growth, where power law coarsening of the mound morphology is observed. For the lateral size of mounds we obtain ξ ∼ t1/z with z≥4. An analytic treatment within a self–consistent mean– field approximation predicts multiscal...
متن کاملTwo-Dimensional Coarsening Kinetics of Reconstruction Domains: GaAs 001 - 2 4
016101-1 We study the nonconserved coarsening kinetics of a reconstructed semiconductor surface. The domain size evolution is obtained in situ by time-resolved surface x-ray diffraction. The system exhibits four equivalent domain types with two nonequivalent types of domain boundaries. Small domains are prepared by molecular beam epitaxy deposition of one GaAs layer. We find the correlation len...
متن کاملLarge scale surface structure formed during GaAs (001) homoepitaxy
Atomic force microscopy studies have been performed on GaAs (001) homoepitaxy Rlrns grown by molecular beam epitaxy. Multilayered features are seen to evolve when the growth conditions favor island nucleation. As the epilayer thickness is increased these features grow in all dimensions but the angle of inclination remains approximately constant at 1”. The mounding does not occur on surfaces gro...
متن کامل