IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Surface Science Thursday Sessions
       Session SS4-ThP

Paper SS4-ThP7
High Resolution AES Mapping and TEM Study of Cu(In,Ga)Se@sub 2@ Thin Film Growth

Thursday, November 1, 2001, 5:30 pm, Room 134/135

Session: Semiconductor Morphology Poster Session
Presenter: C.L. Perkins, National Renewable Energy Laboratory
Authors: C.L. Perkins, National Renewable Energy Laboratory
Y. Yan, National Renewable Energy Laboratory
K.M. Jones, National Renewable Energy Laboratory
R. Noufi, National Renewable Energy Laboratory
Correspondent: Click to Email
The chalcopyrite Cu(In,Ga)Se@sub 2@ (CIGS) shows promise as an absorber layer in thin polycrystalline solar cells, however, many details of this complicated material's growth processes remain unclear. At one point during the so called "three stage" CIGS growth process used at the National Renewable Energy Laboratory (NREL) and elsewhere, the growing film is subjected to a copper rich flux in a selenium ambient. Previous workers have postulated that during this stage there exists a thin film of liquid Cu@sub x@Se at the outermost portion of the CIGS, and that this layer acts as a reservoir of copper as well as a layer in which rapid mass transport is possible. In this paper we present TEM and high resolution AES mapping data taken on samples that had their growth interrupted at a stage when Cu@sub x@Se was expected to be present. The AES maps show CIGS grains which are highly enriched in copper relative to the rest of the CIGS film, and that these same areas contain almost no indium, results consistent with the presence of Cu@sub x@Se. Small area diffraction analysis and energy dispersive spectroscopy (EDS) performed on these same samples independently confirm the presence of Cu@sub x@Se at the surface of growing CIGS films. The implications of these results are discussed in terms of the efficiencies of CIGS photovoltaic devices.