Reflection high energy electron diffraction and Raman scattering show
that the crystalline quality of Sb-doped epilayers is strongly depende
nt on the doping conditions. Surface roughening, which is induced by s
urface segregation of the dopants during growth, degrades the quality
of the film grown and develops with growth. Surface roughening could b
e explained by a two-state-exchange model of Sb segregation.