The Effect of Se Content in Precursors on the Properties of CuInSe_2 Films

摘要

We studied the effect on physical properties of CuInSe_2 (CIS) thin films by change of the Se content in Cu-In-Se precursors. The three kinds of precursors with different Se content were deposited by a hybrid sputtering system which was equipped with the Selenium Knudsen cell (Se K-cell). The precursors were heated in an Se atmosphere for 15 minutes at 425 C, which produced crystalline CIS films. We characterized the crystalline CIS films using scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDS), x-ray diffraction (XRD), and a Hall effect measurement system. The size of the island in the CIS films was reduced with an increasing Se content in the Cu-In-Se precursors. We found that the island structure in the CIS films disappeared with precursors of Se content over 19 at%. We were able to make a highly adhesive CIS film to Mo back contacts by using precursors with Se content of 19 at%. The solar cells fabricated with the CIS films using precursors with an Se content of 19 at% achieved 8.2% efficiency.