The regrowth of(AlGa)As over substrates patterned in [011] directions is an
important step in the fabrication of index-guided laser structures. We pre
sent a detailed study of the influences of growth parameters on the develop
ment of the regrowth front and the composition profile. The overgrown (AlGa
)As exhibits an inhomogeneous Al profile, strongly dependent on growth temp
erature, with less Al on the {311}-sidewalls of the trenches than on planar
facets. The ratio of the growth rate on the sidewalls to the planar growth
rate is used to characterize the development of the growth front, and its
dependence on reactor pressure, growth temperature and trench orientation i
s studied. Differences in the growth behavior for the two trench orientatio
ns are found with overgrowth on [0 (1) over bar 1] trenches being very sens
itive to V/III ratio. This allows an estimation of the efficiency of the As
precursors arsine (AsH3) and tertiary butyl arsine (TBAs) with TBAs being
seven times more effective than AsH3 at 600 degrees C. The observed growth
behavior is discussed in terms of group III mobilities, diffusion processes
and bonding situations on the different surfaces. (C) 1999 Elsevier Scienc
e B.V. All rights reserved.