Two-speed phase dynamics in Si(111) (7x7)-(1x1) phase transition

TL;DR

This paper introduces a two-speed phase-field model for the Si(111) 7x7 to high-temperature phase transition, accurately capturing island decay and experimental observations of surface structural changes.

Contribution

It presents a novel two-speed phase-field model combined with adaptive mesh refinement for simulating Si(111) phase transitions, validated by experimental data.

Findings

7x7 islands decay with shape preservation

Decay rate increases with initial area

Model explains LEEM experimental observations

Abstract

We propose a natural two-speed model for the phase dynamics of Si(111) 7$\times$7 phase transition to high temperature unreconstructed phase. We formulate the phase dynamics by using phase-field method and adaptive mesh refinement. Our simulated results show that a 7$\times$7 island decays with its shape kept unchanged, and its area decay rate is shown to be a constant increasing with its initial area. LEEM experiments concerned are explained, which confirms that the dimer chains and corner holes are broken first in the transition, and then the stacking fault is remedied slowly. This phase-field method is a reliable approach to phase dynamics of surface phase transitions.