This paper investigates CdS/CdTe solar cells treated with various chloride solutions and then annealed in the air before the deposition of the back contact. It was found that the cells with higher efficiency were fabricated using CdCl2 solution treatment and thermal annealing. Such cells are further examined by measuring their current density vs. voltage (J-V) characteristics at various temperatures, quantum efficiency (QE), and capacitance vs. voltage (C-V) characteristics. In addition, the uniformity of the QE across the cells was examined by using the laser beam induced current (LBIC) technique. (C) 2003 Elsevier B.V. All rights reserved.