Cooperative Segregation of Boron at Si(111)

Abstract

Interface segregation of boron at Si(111) surfaces has been studied at the atomic scale using a scanning tunnelling microscope (STM). During the segregation process (produced by thermal annealing), strong cooperative effects take place which cannot be explained by a simple nearest-neighbour pair interaction model. Although average surface concentrations of boron in the investigated temperature range could be calculated in terms of a Fowler's model, the comparison between STM and simulated images suggests that one must introduce longer-range interactions to describe the atomic-scale configurations.

Formation of twinning-superlattice regions by artificial stacking of Si layers

“…Moreover, this procedure is thickness-limited because of the reduction of boron concentration by diffusion broadening. Furthermore, the influences of other disturbing effects like B-clustering [24], oxygen diffusion or SiC formation along the twin formation cannot be excluded.…”

Magic-Sized Diamond Nanocrystals

“…2 can be estimated as 10 21 cm À3 , which is (a) well above the boron density required for insulator-to-metal transition [11][12][13][14], and (b) by an order of magnitude larger than the nominal bulk concentration. Indeed, boron atoms have been known for their tendency to segregate at semiconductor surfaces [37]. under these conditions the boron impurity band considerably broadens and overlaps the diamond valence band edge [15], which causes the system to behave as a degenerate metal with k F % 0:089 A À1 .…”

A STM study on compared chemical reactivities of different Si(111) surfaces: copper growth and ferrocene adsorption

“…Magnifying of the resulting image, not shown here, allows us to estimate the sharpness of the pen. We have obtained letters with a linewidth of 3 nm and the V3 atomic ordering is clearly distinguished on the non-written part of the substrate [17]. 6.…”

“…We present elsewhere a detailed study of this work [17] where we suggest that the involved mechanism might process as follows. First, ionization of ferrocene molecules in the electric field between tip and surface with a maximum of ionization probability under the tip apex.…”

“…First, ionization of ferrocene molecules in the electric field between tip and surface with a maximum of ionization probability under the tip apex. Then, once the molecule is ionized it can react with the substrate and the dissociation occurs, leading to the formation of an amorphous alloy (likely FeSi composition as explained in [17]) while the volatile parts move off. Current experiments to assert this conclusion and characterize the deposited material are undertaken.…”