Interface Properties of (Cd,Zn)S/CuInSe2 Single-Crystal Solar Cells

Metal contacts to p-type CuInSe2 and heterojunctions of the form n-(CdZn) S/p-CuInSe2 have been prepared, to investigate the electrical behavior and chemical composition of the resulting interfaces and to correlate the results with the composition and corresponding electrical properties of CuInSe2. The results indicate that the observed variability of the back contacts and front junctions of different CuInSe2 samples can be attributed to the variable initial equilibrium concentration of the intrinsic defect states which dominate the crystals. The type and concentration of the dominant defects can be changed by thermal treatments and by interface induced effects due to the junction electric field and the chemical potential gradients. Diffusion into or out of the CuInSe2 crystals was not detected. More over, no composition or other chemical variation due to the deposition of the sulfide layer was observed.