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Etching or Stabilization of GaAs(001) under Alkali and Halogen Adsorption

Here are shown the microscopic mechanisms of the selective interaction of iodine and cesium with As-rich B2(2×4) and Ga-rich Chi(4×2) reconstructed GaAs(001) surfaces.
O.E. Tereshenko et al., The Journal of Physical Chemistry C, 116,8535-8540 (2012)

The advanced modifications of epitaxial growth techniques such as migration enhanced and atomic layer epitaxies allow one to grow semiconductor structures in which the interface smoothness and the thickness of layers are controlled with the ultimate precision of one monolayer. Along with atomic-layer growth, for modern nanotechnology, it is important to develop techniques of atomic-layer (“digital”) etching, which consist of layer-by-layer removal of a semiconductor with monolayer resolution. Here it is shown experimentally by photoemission and by ab initio calculations that adsorption of electropositive cesium on the As-rich surface of GaAs(001) and, in a symmetric fashion, adsorption of electronegative iodine on the Ga-rich surface, induce a decrease of the surface stability, thus facilitating surface etching. Conversely, Cs adsorption on the Garich surface and I adsorption on the As-rich surface lead to an increased surface stability. Etching occurs when adsorption-induced charge transfer weakens the backbonds of the top arsenic atoms for the case of Cs on the As-rich B2(2×4) surface and the lateral bonds in the topmost surface layer for I on the Ga-rich Chi(4×2) surface. The possibilities of reversible transitions between the two reconstructed surfaces and of atomic layer etching with monolayer precision are demonstrated.

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Etching or Stabilization of GaAs(001) under Alkali and Halogen Adsorption, O.E. Tereshenko et al, The Journal of Physical Chemistry C, 116,8535-8540 (2012)

Last Updated on Tuesday, 30 September 2014 15:20