On STM imaging of GaAs(0 0 1)-(n × 6) surface reconstructions: Does the (6 × 6) structure exist?

Abstract

The ultrahigh vacuum scanning tunneling microscope (UHV-STM) was employed to investigate the evolution of GaAs(0 0 1)-(n × 6) surface reconstructions. The (n × 6) surface reconstructions have been referred to as As-rich transitional phases comprising of (1 × 6), (2 × 6), (3 × 6) and (6 × 6) reconstructions. During the evolution from (n × 6) to the Ga-rich (4 × 2) reconstruction, our dual-bias (n × 6) STM images reveal one alternating single As dimer chain with a periodicity giving n = 2; and a pair of Ga dimer rows between the As chains with a periodicity of n = 3, which has not been previously reported. A new (6 × 6) reconstruction model is proposed based on the atomic resolution dual bias STM images obtained; and we discuss whether such (6 × 6) reconstructions exist in the light of all STM data published to date. © 2002 Elsevier Science B.V. All rights reserved.