AlGaAs and InGaAlP are important materials for optoelectronic devices. We investigate the effect of p- and n-type doping on the reflectance anisotropy spectroscopy (RAS) spectra of these materials. Different n-dopants (Te, Si) were incorporated to investigate their contribution to the RAS signal at detected photon energies from 2.4 to 4.5 eV. Furthermore, the effect of ordering in GaInP layers on the RAS spectra was studied. Growth parameters such as substrate off-orientation, growth temperature and doping level were varied in order to attain different degrees of ordering in GaInP and study their influence on the RAS signals. These results are combined with capacitance-voltage (C-V) measurements and secondary ion mass spectroscopy (SIMS). (c) 2006 Elsevier B.V. All rights reserved.