A STUDY OF INDIUM DEPLETION IN THE OMVPE GROWTH OF GAINAS

This paper describes an experimental and theoretical study of the nature of indium depletion in the organometallic epitaxy of GaInAs. A mathematical model for mass, momentum and energy transfer, together with homogeneous and heterogeneous decomposition of the indium species, was developed for this purpose. Several different mechanisms were postulated based on experimental data obtained from a mass spectrometric study. The activation energies for the decomposition reactions were obtained by fitting the theoretical composition of GaInAs with the experimental values for growth at 700°C. These models were then compared with experimental results over a range of growth parameters such as susceptor temperature, susceptor slope, reactor pressure and reactant partial pressure. Excellent correlation was obtained for a model based on the homogeneous decomposition of a triethylindium-arsine adduct to a stable product via an irreversible bimolecular reaction, with an activation energy of 11.9 kcal/gmol. This study resulted in the development of a model which describes the nature of the chemical processes that lead to indium depletion. The rate expression obtained for indium depletion can be used to predict the growth rate and composition of GaInAs for a wide range of reactor parameters. Finally, it can be used for optimization of growth and compositional uniformity of GaInAs. © 1990.