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Dimer vacancy (DV) defect complexes in the Si(001)2x1 surface were investigated using high-resolution scanning tunneling microscopy and first principles calculations. We find that under low bias filled-state tunneling conditions, isolated split-off dimers in these defect complexes are imaged as pairs of protrusions while the surrounding Si surface dimers appear as the usual bean-shaped protrusions. We attribute this to the formation of pi-bonds between the two atoms of the split-off dimer and second layer atoms, and present charge density plots to support this assignment. We observe a local brightness enhancement due to strain for different DV complexes and provide the first experimental confirmation of an earlier prediction that the 1+2-DV induces less surface strain than other DV complexes. Finally, we present a previously unreported triangular shaped split-off dimer defect complex that exists at SB-type step edges, and propose a structure for this defect involving a bound Si monomer.
We propose a two-dimensional phase-field-crystal model for the (2$times$1)-(1$times$1) phase transitions of Si(001) and Ge(001) surfaces. The dimerization in the 2$times$1 phase is described with a phase-field-crystal variable which is determined by
Building on our earlier study, we examine the kinetic barriers to decomposition of alane, AlH$_3$, on the Si(001) surface, using the nudged elastic band (NEB) approach within DFT. We find that the initial decomposition to AlH with two H atoms on the
Scanning tunneling microscopy (STM) reveals unusual sharp features in otherwise defect free bismuth nanolines self-assembled on Si(001). They appear as subatomic thin lines perpendicular to the bismuth nanoline at positive biases and as atomic size b
This paper has been withdrawn by the authors (see text).
We perform total energy calculations based on the tight-binding Hamiltonian scheme (i) to study the structural properties and energetics of the extended {311} defects depending upon their dimensions and interstitial concentrations and (ii) to find po