(BGaIn)As and (InGa)(NAs) have been tested for the application in solar cells. Single layers have been grown lattice matched on GaAs using MOVPE at low growth temperatures. Optical properties, i.e. band-gap energies and optical constants have been determined with photo luminescence and spectroscopic ellipsometry. n- and p-Type doping have been achieved with disilane and diethylzine as doping precursors, respectively. Corresponding free carrier properties are discussed based on Hall measurements. Different solar cell structures with n- and p-doped (BGaIn)As and (InGa)(NAs) as base layer have been grown and successfully tested. (C) 2004 Elsevier B.V. All rights reserved.