Conversion efficiencies as high 15.3% (17% when corrected for contact area) have been obtained for single‐crystal antireflection‐coated GaAs solar cells fabricated without the use of Ga1−xAlxAs layers. These devices employ a thinn+/p/p+structure prepared by chemical vapor deposition, in which surface recombination losses are reduced because then+layer is so thin (1300 A˚) that most of the carriers are generated in theplayer below the junction.