The alternative As-precursor tertiarybutylarsine (TBAs) is used to grow (AlGa)As-GaAs heteroface solar cell structures. In a horizontal reactor (AIX200) a low growth temperature of 625 degreesC and a low V/III-ratio of 10 was used, Solar cell structures using a arsine (AsH3)-based MOVPE process were grown in a multi-wafer reactor (AIX2600G3) using growth temperatures of 700 degreesC and a V/III-ratio of 31. The solar cell efficiencies of both structures are 24.2% (AM 1.5 g). The obtained efficiency values are state of the art and demonstrate that TBAs can be an alternative to the more commonly used arsine with no decrease in the solar cell performance. (C) 2001 Elsevier Science B.V. All rights reserved.