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Dissociative Adsorption and Desorption Processes of Cl2/GaAs(001) Surfaces

Published online by Cambridge University Press:  10 February 2011

Takahisa ohno
Takahisa ohno*
Affiliation:
National Research Institute for Metals, Tsukuba-shi, Ibaraki 305, Japan
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Abstract

The energetics of both dissociative adsorption of C12 molecules on reconstructed GaAs(001) surfaces and desorption of chlorides from the chlorinated GaAs(001) surfaces is theoretically investigated, employing the first-principles pseudopotential density-functional approach within the generalized gradient approximation. On the Ga-rich GaAs(001)-(4x2) surface a C12 molecule is found to dissociate with no potential barrier over a Ga dimer and the Ga dimer is also simultaneously broken upon chlorination, resulting in formation of GaC1 with two backbonds to the As layer below. The desorption energy of a GaCl molecule is smaller than that of a Cl atom, although the former involves breaking two Ga-As backbonds and the latter involves the breakup of one Ga-Cl bond. On the As-rich (2x4) surface, the dissociation of a C12 molecule over an As dimer is an activated process and the As dimer is not broken by the Cl adsorption. The desorption energy of a AsCI molecule is larger than that of a Cl atom. The obtained results are consistent with recent experiments such as temperature-programmed desorption measurements.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 408: Symposium P – Materials Theory, Simulations, and Parallel Algorithms , 1995 , 451
Copyright
Copyright © Materials Research Society 1996

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