Diffusion, nucleation and annealing of Co on the H-passivated Si(100) surface

Abstract

We investigate the diffusion, nucleation and annealing behaviour of Co on H-passivated Si(100) surfaces by scanning tunneling microscopy (STM). Due to the absence of nucleation sites for silicide formation, the nucleation and growth mode is dominated by the formation of non-epitaxial islands which merge by increasing Co coverage h. The island number density N shows a power law dependence on coverage N3hc (c=0.29±0.03) for room temperature deposition. Annealing at temperatures up to~400°C results in small changes of the Co clusters, while deposition at elevated substrate temperatures (~400°C) results in the formation of fewer but coarser Co islands. Finally, at higher annealing temperatures (~490°C) where H desorption takes place, the formation of twodimensional islands occurs which are surrounded by an irregular 2×n (n>1) reconstructed surface due to interstitial diffusion of Co into Si.

Epitaxial growth of CoSi2 on hydrogen-terminated Si(001)

“…10 The reaction was found to be prohibited on the hydrogen-terminated Si. [11][12][13][14] Thus, the surfaceterminating hydrogen, which may be present on Si surfaces after deposition of metal atoms, is expected to suppress the formation of low-temperature Co silicide phases upon annealing. In this study, we investigate reactions of Co on H-terminated Si͑001͒ ͑H-Si͒ and demonstrate the epitaxial growth of CoSi 2 .…”

Fabrication of Co/Si nanowires by ultrahigh-vacuum scanning tunneling microscopy on hydrogen-passivated Si(100) surfaces

“…Similar behavior was also observed for Co on hydrogen-passivated Si͑100͒ surfaces ͑H-Si͑100͒͒ prepared in UHV and studied in situ by STM. 12 This behavior is quite different from the behavior of submonolayer growth of Co on bare Si͑100͒ where the missing passivation layer allows interstitial diffusion and the reaction of Co with the Si substrate. 7 However, selective nucleation of Co adatoms on locally depassivated H-Si͑100͒ surfaces for nanoscale metallization still remains unexplored.…”

“…12 We therefore choose for a study in the submonolayer regime. From the present study we can conclude that 0.2-0.4 ML of Co should be sufficient for the formation of a closed metallic wire.…”

“…From the present study we can conclude that 0.2-0.4 ML of Co should be sufficient for the formation of a closed metallic wire. The necessary amount of Co might even be reduced by deposition at elevated substrate temperature 12 which would lead to an increased material transport to the depassivated areas. For closing of the film on the H-passivated area coverages in the ML regime ͑3-6 ML͒ are expected ͑see also Ref.…”

Co growth on Si(001) and Si(111) surfaces: Interfacial interaction and growth dynamics

“…As such, the study of growth and structure of thin films deposited on hydrogen-terminated Si surfaces have been investigated for a great variety of metals. Examples include 3d-transition metals such as Ti, Fe and Ni [16][17][18][19][20], the noble metals such as Cu, Ag and Au [21][22][23], and the trivalent simple metals such as Al and In [24][25][26]. In some of these studies, hydrogen behaves as a ''surfactant'' which not only suppressed the formation of three dimensional islands [16] but also interfacial metal silicides [24][25][26].…”