The formation of multi-atomic steps (step-flow growth with step-bunching) on the surface of 111-V semiconductor compounds during metal-organic vapor-phase epitaxial (MOVPE) growth is a phenomenon of considerable significance. As low-dimensional material arrangements are widely used in novel opto-and/or microelectronic devices, it is of great importance and fundamental interest to determine the correlation between variations of the crystal surface during the growth process and the in-situ development of microstructures. This behavior is also referred to as in-situ self-organization of MOVPE grown material.
Matsumoto et al.
['] interpreted their photoluminescence spectra of (Al,Ga)As/GaAs single quantum wells as resulting from the terrace structures of different sizes, perpendicularly oriented to the growth direction of the GaAs wells. The topographical evolution of the (001) GaAs surface annealed under arsine/hydrogen ambient was recently studied by atomic force microscopy (AFM) and in-situ diffuse optical light scattering.[21 Likewise, reflectance anisotropy spectroscopy (RAS) is a highly surface-sensitive technique which is suitable for an in-situ MOVPE growth control and for the study of surface structure and surface reconstruction.
Reinhardt et al.r3J showed that the surface structure of MOVPE grown layers is influenced by the growth parameters v/III ratio, growth temperature (Tgrowth), and TMGa input partial pressure (PTMG~). The recorded RAS spectra permit the differentiation of at least three modes of MOVPE growth: i) With growth conditions usually used in low-pressure MOVPE of GaAs, a c(4 x 4) surface [*I Dr.