Growing smooth epitaxial layers on misoriented substrates

Abstract

A process for improving the smoothness of semiconductor layers grown by epitaxy is described. Smooth epitaxial layers, free of crystal terraces, are attained by misorienting the growth surface of the substrate from a major crystallographic plane by a small critical angle approximately equal to the tread-to-riser angle of terraces which would be formed if the epitaxial layer were deposited on a growth surface nominally parallel to the major plane. The critical angle is a function of both the growth temperature and the crystal composition. Specific examples for the growth of LPE Al.sub.x Ga.sub.1-x As at various growth temperatures and values of x on GaAs substrates misoriented from the (100) and (111)B major planes are given. Also described are examples of silicon layers grown by CVD on (111) substrates to measure the critical angle in the (112) direction.

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