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An Evaluation of Simplified Models for Surface Kinetics in Movpe Processes

Published online by Cambridge University Press:  25 February 2011

Max Tirtowidjojo  and
Richard Pollard
Max Tirtowidjojo
Affiliation:
Department of Chemical Engineering, University of Houston, Houston, TX 77204
Richard Pollard
Affiliation:
Department of Chemical Engineering, University of Houston, Houston, TX 77204
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Abstract

A general MOVPE model has been used to assess the applicability of simplified representations for surface kinetics. With the general model, predictions for GaAs deposition on (111 )Ga using trimethylgallium and arsine show excellent agreement with observed growth rates. However, if Langmuir-Hinshelwood kinetics is assumed, the model only matches the deposition rates over a narrow range of operating conditions, even when several rate-limiting steps are included. This limitation arises because combinations of equilibrium constants and local partial pressures often do not give reasonable approximations for the surface concentrations of reactive intermediates. The form of the Langmuir-Hinshelwood relation(s) and the parameter values can be fitted empirically to experimental data, but this could lead to erroneous conclusions concerning process behavior and the model would have limited predictive capabilities. An alternative approach is to use surface reaction probabilities, but they can only be applied in an empirical fashion and their magnitudes depend on gas flow rate, inlet composition, and reactor pressure as well as surface temperature.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 131: Symposium E – Chemical Perspectives of Microelectronic Materials I , 1988 , 109
Copyright
Copyright © Materials Research Society 1989

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References

REFERENCES

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