Formation of Double Steps on Si (100): Effect of Permeability of the A-Steps
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PHYSICS OF SEMICONDUCTORS AND DIELECTRICS FORMATION OF DOUBLE STEPS ON Si (100): EFFECT OF PERMEABILITY OF THE A-STEPS Yu. Yu. Hervieu
UDC 538.97:539.216.2:539.23
A model of the elementary step motion on a two-domain (100) silicon surface during crystallization from a molecular beam is proposed. The model takes into account the possibility of an adatom transition to an adjacent terrace before incorporation into a kink at the A-step edge (the effect of the A-step permeability). It is shown that the permeability of the A-step contributes to the faster pairing of the A- and B-steps and, consequently, transition to a single-domain surface. For the fast pairing of the steps, it is sufficient only the presence of an inverse Ehrlich–Schwoebel barrier for the attachment of adatoms to the A-step from the B-type terrace. A conventional barrier (for the attachment from the A-type terrace) may be absent, which is consistent with the results of quantum chemical calculations. Keywords: silicon, surface, reconstruction, steps, kinks, diffusion.
INTRODUCTION The dynamics of monatomic steps on the vicinal Si(100) – (21) surface is of interest for preparation of surface optimal for the formation of various semiconductor epitaxial structures [1–3]. Studies of the initial stage of epitaxial growth of silicon on this surface have shown that under certain conditions, fast transition (during the growth of half a silicon monolayer) from a two-domain surface to a single-domain one occurs due to the fast motion of monatomic Btype steps in the absence of motion of the A-type steps [4 ]. In [5], such a fast pairing of steps is explained by the presence of both the conventional and inverse Ehrlich–Schwoebel barriers [6, 7] for the attachment of adatoms to the edge of the A-step. However, the results of quantum chemical calculations indicate the absence of the conventional barrier [8]. In this paper, we propose a model of step motion that takes into account the A-step permeability, i.e. the possibility of transitions of adatoms to a neighboring terrace without preliminary joining the kinks at the edge of the step [9, 10]. The rates of the steps are determined from the solution of the corresponding boundary value problem for surface diffusion of adatoms. For the kinetic coefficients and the permeability coefficient of the A-step that appear in the boundary conditions, expressions are used that were obtained using the model of the adatom incorporation into the permeable step [10]. The model demonstrates the possibility of fast pairing of steps in the absence of the conventional Ehrlich–Schwoebel barrier.
MODEL It was assumed that the two-domain Si (100) surface is a vicinal surface misoriented by a certain angle from the singular (100) face in the [110] direction. On the surface, there are monatomic steps of two types – А and В, whose
National Research Tomsk State University, Tomsk, Russia, e-mail: [email protected]. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 3–7, June, 2020. Original article submitted Decemb
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