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Au-GaAs Reaction Kinetics: Its Role in Fabrication of Ohmic Contacts
Published online by Cambridge University Press: 25 February 2011
Abstract
Annealing of Au/GaAs leads to vaporization of As species and migration of Ga atoms into Au. These processes are simultaneous only on a macro-scale. A simple kinetic model is developed in which they are treated sequential by introducing specific fluxes F(Ga) and F(As). F(Ga) is calculated assuming linear flow at the phase boundary. F(As) is set constant for a given external pressure of arsenic. The model accurately describes the observed reaction rate in both capped and open configuration. It is shown that instantaneous composition of GaAs surface adjacent to the metal evolves from initially As-rich to Ga-rich when Au becomes saturated with Ga. The model is consistent with common observation that short-time heating of Au(dopant)/GaAs activates dopant species preferentially on Ga vacant sites. To activate dopants in As sublattice longer times and/or higher temperatures are needed.
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- Copyright © Materials Research Society 1992
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