Contact angles between (GaAl)As solid and solutions

Liquid phase epitaxy (LPE) is a solution growth process in which the solid phase is not totally enclosed by the solution during growth; in the case of the commonly used (GaAl)As system the solution has a finite angle of contact with the solid. The purpose of this paper is to demonstrate that as a consequence a ridge forms on the surface of a wafer around the periphery of the solution, consistent with the solid surface being deformed to the equilibrium angles with the liquid and vapor phases. The phenomenon is demonstrated using an unconstrained drop of a saturated solution on a horizontal wafer, while we also report measurements of the interfacial surface tensions between the three phases. The relationship to the edge ridge commonly observed on wafers grown by LPE is discussed. © 1983.