The GaAs(112)A and B surfaces were prepared by molecular beam epitaxy (MBE) and characterized in situ by scanning tunneling microscopy (STM). Both surfaces an unstable. On the (112)A surface Eve facets with the orientations (111), {110} and {124} appear, while on the ((112) over bar)B surface four facets with the orientations ((111) over bar)B, ((110) over bar) and ((113) over bar)B were observed. In both cases, the facets form depressions covering the entire surface. In addition, total-energy calculations employing density-functional theory were carried out for these surfaces. For the (112)A surface a roof-like structure of {111} and {113} planes has the lowest calculated energy. According to the calculations, the ((112) over bar)B surface forms under As-rich conditions a roof-like structure of {(111) over bar} and {(113) over bar}B planes, and it decomposes under Ga-rich conditions into {<(11)over bar>0} planes. The experimental and theoretical findings for the {(112) over bar}B surface are in good agreement. The occurrence of {124}-facets on the (112)A surface was not taken into consideration in the calculations and needs to be investigated further.
A scanning tunneling microscopy study of the GaAs(112) surface
RUGGERONE, PAOLO;
1999-01-01
Abstract
The GaAs(112)A and B surfaces were prepared by molecular beam epitaxy (MBE) and characterized in situ by scanning tunneling microscopy (STM). Both surfaces an unstable. On the (112)A surface Eve facets with the orientations (111), {110} and {124} appear, while on the ((112) over bar)B surface four facets with the orientations ((111) over bar)B, ((110) over bar) and ((113) over bar)B were observed. In both cases, the facets form depressions covering the entire surface. In addition, total-energy calculations employing density-functional theory were carried out for these surfaces. For the (112)A surface a roof-like structure of {111} and {113} planes has the lowest calculated energy. According to the calculations, the ((112) over bar)B surface forms under As-rich conditions a roof-like structure of {(111) over bar} and {(113) over bar}B planes, and it decomposes under Ga-rich conditions into {<(11)over bar>0} planes. The experimental and theoretical findings for the {(112) over bar}B surface are in good agreement. The occurrence of {124}-facets on the (112)A surface was not taken into consideration in the calculations and needs to be investigated further.
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