Fabrication of CdS/CdTe Solar Cells by Quasiclosed Space Technology and Research of Their Properties

Abstract

A quasiclosed space technology has been developed for the deposition of CdS and CdTe layers, while fabricating solar cells (SCs). Technological factors affecting the crystal lattice structure, the optical band gap width, and the conductivity in the CdS and CdTe layers are studied and analyzed. A technology to produce an ohmic contact with p-CdTe, by using the degenerate CuxS semiconductor, is proposed. The characteristics of SCs fabricated on substrates covered with various conducting films (Mo, ZnO, ZnO:Al) are analyzed. The measurement results of light and dark voltage-current characteristics testify to the better characteristics of ZnO and ZnO:Al films obtained by the atomic layer deposition from the viewpoint of their application in SCs. The optimum thicknesses of the CdS (67 nm), CdTe (about 1 /um), and CuxS (30 nm) layers, at which the best SC efficiency (n = 1.75÷1.89%) is obtained, are determined. The application of thin films in SC structures is shown to improve the characteristics of the latter.