Introduction to Step Dynamics and Step Instabilities

ABSTRACTHow the surface morphology of a low index crystal surface evolves under annealing below the roughening temperature is still being investigated both theoretically and experimentally. This research is needed to understand the stability of nanostructures and for the control of step array on surfaces for various technological applications.We have approached this problem from an experimental point of view by looking at the step morphology on the top of mesas patterned on Si(111) after flashing at 1200°C and annealing between 1000–1100°C. We find that after annealing, nanometer height ridges develop on the edges of the mesas except for one edge which becomes a source for steps advancing into the mesa top. The edge that does not develop a ridge is mainly determined by the initial miscut of the surface.We attempt to explain our results through step dynamics and present some applications of this phenomena in creating novel arrays of steps.

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Spontaneous Formation of Ridges on Patterned Mesas and Their Role in the Evolution of

MRS Proceedings ◽

10.1557/proc-854-u2.5/jj2.5/kk2.5 ◽

2004 ◽

Vol 854 ◽

Author(s):

Step Arrays ◽

Kee-Chul Chang ◽

Jack M. Blakely

Keyword(s):

Computer Simulations ◽

One Dimensional ◽

Step Motion ◽

Spontaneous Formation ◽

Terrace Width ◽

Sinusoidal Shape ◽

Step Dynamics ◽

Step Step

ABSTRACTMesa structures fabricated on Si(111) surfaces have been found experimentally to develop step arrays with large spacing of the order of a micron or more after annealing at temperatures where sublimation becomes important. Ridges around the edges initially develop during annealing and form barriers to step motion before eventually breaking down. This produces an array of steps of the same sign with a few wide terraces. Computer simulations using one dimensional Burton, Cabrera and Frank (BCF) theory including attachment-detachment rates and step-step repulsion for this configuration show that the terraces evolve under different dynamics depending on the terrace widths. For large terrace widths, sublimation dominates the step dynamics and the Ehrlich-Schwoebel effect is negligible. Sinusoidal terrace width distributions result in this case. The experimentally measured step distribution has such a sinusoidal shape suggesting that the step dynamics is sublimation dominated on the mesas after ridge breakdown.

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