Vacuum-evaporated, CdCl2-doped cadmium sulfide films for solar cell applications

CdCl2-doped CdS films have been prepared using a vacuum evaporation technique with a goal of providing a low resistivity, large grain size, window layer for CdTe/CdS solar cells. CdS films with 0.05, 0.1 and 0.2% CdCl2 doping have been grown. The effects of doping on the optical transmission, XRD, resistivity, carrier concentration, Hail mobility, and microstructure have been investigated. N-type CdS films with resistivities of 2 to10 Omega -cm and Hall mobilities from 1 to 5 cm(2)/V-sec have been grown using this technique. The XRD patterns show that [002] is the preferred orientation. SEM analyses reveal that the grains in the films are columnar and their size increases from 70 nm for undoped CdS films to 150 nm for 0.2% CdCl2-doped films.