Reconstruction of the GaAs(001) surface induced by submonolayer Si deposition

Abstract

We have studied the change of the GaAs(001) surface reconstruction due to Si deposition by reflection high-energy electron diffraction and scanning tunneling microscopy (STM). We find that with increasing Si deposition below 15% of a monolayer at substrate temperatures above 600 \ifmmode^\circ\else\textdegree\fi{}C new reconstructions form that are not observed on the initial surface. The initial surface, prepared by molecular-beam epitaxy, is the (2\ifmmode\times\else\texttimes\fi{}4) As-stabilized reconstruction. STM reveals straight missing dimer rows with two As dimers per unit cell. With an increasing amount of Si deposited on this surface, the reconstruction shows an increasing disorder due to kinks that develop in the missing dimer rows. The Si deposition leads to an overall decrease of the As coverage. After a Si deposition of 5% of a ML a new Ga stable (3\ifmmode\times\else\texttimes\fi{}2) reconstruction starts to develop. With further increasing the Si concentration or the substrate temperature at this Si level, the surface continues to get more Ga stable transforming via a (5\ifmmode\times\else\texttimes\fi{}2) to a (4\ifmmode\times\else\texttimes\fi{}2) reconstruction.