Electrical and optical properties of boron doped CdS thin films prepared by chemical bath deposition

Boron doped CdS films were prepared by chemical bath deposition, which is a low-cost and large-area technique and appears to be well-suited for the manufacture of thin film solar cells, using boric acid (H3BO3) as dopant source, and their properties were investigated as a function of doping concentration. In addition, effects of the boron doping of the CdS films on the characteristics of CdS/CdTe solar cells were investigated. As the boron doping concentration increased, the resistivity of CdS films rapidly decreased and exhibited the lowest resistivity of 2 Ω cm at 0.01 of H3BO3/CdAc2 mole ratio. Boron doping into CdS films improved the optical transmittance in the visible region of light and increased the optical band gap. The photovoltaic characteristics of CdS/CdTe solar cells using boron doped CdS film as the window layer were improved due to the increase of the electrical conductivity and the optical band gap of CdS films.