Phase transition between (2 x 1) and c(8 x 8) reconstructions observed on the Si(001) surface around 600C

TL;DR

This study investigates the reversible phase transition between (2 x 1) and c(8 x 8) reconstructions on the Si(001) surface around 600°C, using RHEED and STM techniques during ultrahigh vacuum treatments.

Contribution

It reveals the temperature-dependent and reversible phase transition between surface reconstructions on Si(001), linking RHEED patterns to atomic-scale structures observed by STM.

Findings

(4 x 4) pattern appears at T <~600°C during cooling

c(8 x 8) structure confirmed by STM at room temperature

Transition depends on thermal treatment conditions and cooling rate

Abstract

The Si(001) surface subjected to different treatments in ultrahigh vacuum molecular beam epitaxy chamber for SiO$_2$ film decomposition has been in situ investigated by reflected high energy electron diffraction (RHEED) and high resolution scanning tunnelling microscopy (STM). A transition between (2 x 1) and (4 x 4) RHEED patterns was observed. The (4 x 4) pattern arose at T <~600C during sample posttreatment cooling. The reconstruction was observed to be reversible. The c(8 x 8) structure was revealed by STM at room temperature on the same samples. The (4 x 4) patterns have been evidenced to be a manifestation of the c(8 x 8) surface structure in RHEED. The phase transition appearance has been found to depend on thermal treatment conditions and sample cooling rate.