Temperature dependence of surface roughening during homoepitaxial growth on Cu(001)

Temperature-dependent vacancy formation during the growth of Cu on Cu(001)

“…Because the presence of vacancies is likely to influence the microscopic kinetic mechanisms that govern the growth on these surfaces, the process of vacancy formation could lead to very significant changes in surface morphology for low-T homoepitaxy. In a previous x-ray scattering study 4 we reported the first experimental indication that a large compressive strain, consistent with the incorporation of an appreciable vacancy concentration ͑ϳ2%͒, is present in a 15-ML-thick Cu film deposited on Cu͑001͒ at Tϭ110 K. Recently, we obtained similar results for the low-T Ag/Ag͑001͒ and Ag/Ag͑111͒ epitaxy and showed that in the case of Ag͑111͒ the vacancies have a strong effect on the surface morphology. 10 Here we report x-ray scattering measurements of the temperature and coverage dependence of vacancy formation during the growth of Cu on Cu͑001͒.…”

“…For the film grown at 160 K, the only change in the reflectivity from its ideal ͑perfectly truncated crystal͒ profile is a more accentuated dampening at Q z -values far from the in-phase condition. This behavior is a consequence of the surface roughness that increases with the coverage and has been thoroughly analyzed in our previous studies of kinetic roughening 3,4,22 using a model 22 that assumes height fluctuations described by Poisson statistics. The dashed lines in Fig.…”

“…We investigated Cu films with thicknesses in the range 2.5-20 ML, deposited at temperatures between 110 and 160 K. X-ray scattering is a particularly useful probe for these studies because of its unique ability to measure the surface morphology and the subsurface structure simultaneously. Previously, x rays have been used to study mismatches between the deposited film and the underlying bulk of the crystal induced by either surface relaxation, 18,19 incorporated defects, 4 and surface reconstructions. 20 Our specular reflectivity data conclusively show that a compressive strain along the surface normal is present in the deposited films, which indicates that vacancies are incorporated through the growing surface.…”

“…Indeed, experimental and theoretical studies of metal homoepitaxy have shown that many quantities that describe the morphology of the evolving surface ͑such as the mean-square roughness 2 or the growth exponent ␤͒ exhibit a pronounced temperature dependence. [1][2][3][4][5][6][7][8][9][10] Moreover, growth at different temperatures may progress in different modes, leading to qualitatively different surface morphologies, like in the case of Ag/Ag͑001͒ epitaxy, where the surface was observed to grow via the propagation of steps ͑step flow͒ for TϾ500 K, laterally ͑layer by layer͒ for 500 KϾTϾ200 K or vertically for T Ͻ200 K. 3 While it is obvious that at high enough temperatures T influences growth via the atomic surface mobility, its effects on the surface morphology at ''very'' low temperatures ͑where the adatom mobility is small͒ are much less understood. Recently, it was found that certain metallic surfaces, where homoepitaxy is dominated by an additional energy barrier that opposes the interlayer mass transport ͓Ehrlich-Schwoebel ͑ES͒ effect͔, 11 exhibit a strong temperature dependence of growth within the low-T regime.…”

Variation of growth morphology with chemical composition of terraces: Ag on a twofold surface of a decagonal Al-Cu-Co quasicrystal

“…This has been reported for homoepitaxy on Pt͑111͒, 34 Rh͑111͒, 35 Ag͑100͒, 36,37 and Cu͑100͒. 38 The unexpected feature is the formation of smooth films at low temperature. Although a slightly different model has been put forward to explain each system, all explanations share two basic features.…”