CHANGES IN THE ELECTRONIC-STRUCTURE OF CUINS2 THIN-FILMS BY NA INCORPORATION

For Na-free and Cu-deficient CuInS2 thin films with chalcopyrite struc ture, electron spectra of core levels and valence band were similar to each other in spite of a difference in Cu deficiency. Incorporation o f Na with the CuInS2 films caused peak shifts by -0.5 eV for the core levels without changes in both linewidth and shape. The electron densi ty of states, deeper by 1-5 eV than that from Cu d-S p hybridization c entered at around 2.5 eV, increased by the Na incorporation, and incre ments in the electron density of states, were larger for the films wit h larger the Cu deficiency. The Na incorporation yielded a surface lay er expressed as (Na,Cu)InS2 on the Cu deficient CuInS2 films. (C) 1998 American Institute of Physics, [S0003-6951(98)03236-7].