Ab initiostudy of subsurface diffusion of Cu on the H-passivated Si(001) surface

Abstract

In this paper we use density-functional theory calculations to analyze both the stability and diffusion of Cu adatoms near and on the H-passivated Si͑001͒ surface. Two different Cu sources are considered: depositing Cu from vacuum, and contaminating Cu outdiffusing from bulk Si. Deposited Cu from vacuum quickly moves subsurface to an interstitial site in the third Si layer ͑T2͒. Once there, Cu adatoms enter a subsurface zigzag migration route between T2 and another subsurface site, T2 → HSL→ T2, along the dimer row direction. Contaminating Cu outdiffusing from bulk is found to be a fast diffuser along both parallel and perpendicular directions to the dimer row when far from the surface. It is attracted to the layers close to the surface and becomes trapped at an interstitial site located at the sixth Si layer ͑T3͒. As the outdiffusing Cu atoms get closer to the surface, a channeling zigzag diffusion along the dimer row direction, similar to that one followed by deposited Cu from vacuum, is favoured over diffusion along the perpendicular direction. These results are consistent with previous experimental work done on similar systems and will motivate further experiments on the interesting interaction between Cu and Si surfaces.

Scalable Patterning of One-Dimensional Dangling Bond Rows on Hydrogenated Si(001)

“…Energy differences are converged to within 0.01 eV and forces to 0.02 eV/Å. We used a unit cell which was one dimer row wide, 10 dimers long, and 10 layers deep, with the bottom two layers fixed and the bottom layer terminated with hydrogen. , The commonly used scheme to simulate STM images is based on the Tersoff-Hamann approximation which asserts that the LDOS is proportional to the tunneling current. STM simulations correspond to the integral of all the partial charge densities for the bands between the bias voltage and the Fermi level, assuming that the tip has a flat density of states.…”

Endotaxial Si nanolines in Si(001):H

“…We used a unit cell which was one dimer row wide, ten dimers long and ten layers deep, with the bottom two layers fixed and the bottom layer terminated with hydrogen. [33,34]…”

Diverse growth of Mn, In and Sn islands on thallium-passivated Si(111) surface

“…Based on the presented data, we suggest two possible scenarios of the creation of Sn-Tl islands. Deposited Sn atoms either diffuse on the passivating layer or directly penetrate deeper into the Si(1 1 1)/Tl − (1 × 1) surface and diffuse there (the possibility of sub-surface diffusion channels on passivated Si surfaces has been previously shown [26]). The Sn-Tl reconstructed islands form at sites with sufficiently high local concentration of Sn atoms.…”