A Simple Sb^sub 2^Te^sub 3^ Back-Contact Process for CdTe Solar Cells

CdTe solar technology has proved to be a cost-efficient solution for energy production. Formation of the back contact is an important and critical step in preparing high-efficiency, stable CdTe solar cells. In this paper we report a simple CdTe solar cell (Sb^sub 2^Te^sub 3^) back contact-formation process. The CdS and CdTe layers were deposited by close-space sublimation. After CdCl^sub 2^ annealing treatment, the CdTe surface was etched by use of a mixture of nitric and phosphoric acids to obtain a Te-rich surface. Elemental Sb was sputtered on the etched surface and successive post-annealing treatment induced Sb^sub 2^Te^sub 3^ alloy formation. Structural characterization by x-ray diffraction analysis confirmed formation of the Sb^sub 2^Te^sub 3^ phase. The performance of solar cells with nanoalloyed Sb^sub 2^Te^sub 3^ back contacts was comparable with that of reference solar cells prepared with sputtered Sb^sub 2^Te^sub 3^ back contact from a compound sputter target.