Microscopic Observation of a Superstructure Phase Transition: In/Si(100)

Abstract

The PAC method has been used to study the (2 × 2) In → (4 × 3) In superstructure phase transition on Si(100) 2 × 1. About 0.05 ML natural In doped by a small amount of the radioactive probe isotope 111In was deposited on a Si(100) 2 × 1 surface. Two different electric-field gradient situations are found and attributed to the low-concentration precursors of the (2 × 2) In and (4 × 3) In superstructures, respectively. The (2 × 2) In → (4 × 3) In phase transition has been studied as a function of annealing temperature and time, revealing a critical temperature of 610(20) K in contrast to earlier investigations. The results are compared to recent STM investigations of the low-concentration adsorption behaviour of In on Si(100) 2 × 1.