Existence of metastable step density distributions on GaAs(100) surfaces and their consequence for molecular beam epitaxial growth

Abstract

Variations in the static and steady‐state specular beam intensity (I₀ and I_S, respectively) in reflection high‐energy electron diffraction from GaAs(100) have been examined as a function of substrate temperature (T_S) and As₄ pressure in molecular beam epitaxy. At a fixed As₄ pressure, regimes of reversible and irreversible behavior of I₀ and I_S as a function of T_S are identified. The irreversible regime of I₀ is shown to occur at temperatures close to the congruent temperature. At each temperature in this regime, the existence of smoothest, but metastable, surface step density configuration is demonstrated. The maximum in I_S is found to occur in this regime. The surface kinetic processes responsible for this behavior are discussed.