Density functional theory and second-order Moller-Plesset perturbation theory investigations show that carbon-rich semiconductor microclusters GelSimCn (7less than or equal tos=l+m+nless than or equal to10 with n=5-8) possess linear or planar structures and the aromaticity of the singly- or doubly charged H-saturated planar derivatives with (4n+2) delocalized pi electrons decreases with the increasing of noncarbon atoms. (C) 2003 American Institute of Physics.