Scanning Microscopy


GaAs(100), (110), and (111) surfaces are chosen as a vehicle to explain the plethora of surface relaxation and reconstruction phenomena seen for III-V compound semiconductors. These relaxation and reconstruction processes directly affect the formation of surface states. The occupation of these states, in turn, can have a profound influence on device performance. The purpose of this work is to attempt to provide a unified description of the phenomena responsible for surface relaxation and reconstruction on these surfaces. Our work makes use of an ab initio effective core potential scheme based on the Hartree Fock approximation. We discuss the critical steps involved in both the surface reconstruction process and surface energy band structure evolution for (100) surfaces. It is shown that the reconstruction mechanism is driven by the need to satisfy the surface dangling bonds and by a steepening relaxation. (111) A and B surface reconstruction is discussed by reference to Ga6As6H18 model cluster calculation results. The importance of site specific chemical character on bonding and reconstruction is underlined. The main factors responsible for relaxation and reconstruction of III-V compound semiconductor surfaces are thus shown to include satisfying dangling bonds, steepening relaxation and site specific chemical character.

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