A study of the surface structure and composition of annealed Ga0.96Mn0.04As(1 0 0)

The surface structure and chemical composition of annealed Ga0.96Mn0.04As(1 0 0) have been studied by scanning tunneling microscopy (STM), auger electron spectroscopy (AES) and low energy electron diffraction (LEED). The samples were As capped and subsequently transferred in-air from the MBE system to the STM chamber. After annealing to 600 K it is found that the Mn segregates to the surface and forms a compound, which is stable up to annealing temperatures of 790 K. For annealing temperatures above 825 K a well-ordered phase exists signified by a LEED pattern consisting of a superposition of a ð1 6Þ and a ð4 2Þ pattern. LEED and STM measurements demonstrate that the surface is dominated by ð1 6Þ domains coexisting with small patches of ð4 2Þ domains. By comparing the STM images of the high temperature phase found on Ga0.96Mn0.04As(1 0 0) with the high temperature phases found on ordinary GaAs(1 0 0), we demonstrate differences between annealed Ga0.96- Mn0.04As(1 0 0) and GaAs(1 0 0) in both surface morphology and atomic structure.We argue that the Ga0.96Mn0.04As surface is more As rich than the GaAs surface prepared in a similar fashion. Reasons for these differences are discussed. # 2003 Elsevier B.V. All rights reserved