ROLE OF THERMOSOLUTAL CONVECTION IN LIQUID-PHASE ELECTROEPITAXIAL GROWTH OF GALLIUM-ARSENIDE

This article investigates the effect of thermosolutal convection in li quid phase electroepitaxial (LPEE) growth of GaAs through a two-dimens ional numerical simulation model. The model accounts for heat transfer and electric current distribution with Peltier and Joule effects, dif fusive and convective mass transport including the effect of electromi gration, and fluid flow coupled with temperature and concentration fie lds. Simulations are performed for two growth cell configurations and the results are analyzed to determine growth rates, substrate shape ev olution, and relative contributions of Peltier cooling and electromigr ation. The simulations predict and help explain a number of experiment ally observed features which previous diffusion-based models fail to r eproduce. In general, electromigration is found to be the dominant gro wth mechanism, but the contribution of Peltier cooling to the overall growth rate is found to be significantly enhanced by thermosolutal con vection in the solution, and Peltier cooling can in fact become the do minant growth mechanism for certain growth conditions and growth cell configurations. The overall growth rate is found to increase with incr easing furnace temperature and applied electric current density. The t hermosolutal convection model predicts increased non-uniformity of the grown layers compared with the pure-diffusion model. The shape of the grown layers is also shown to be very sensitive to changes in growth cell configurations.