Secondary and polymorphic phase behavior of thin film CuInSe/sub 2/: ramifications on the device performance

The microstructure of polycrystalline thin film CuInSe/sub 2/ is investigated by spectrophotometry, X-ray diffraction, and transmission electron diffraction as a function of composition and relevant processing parameters. The inter- and intragranular microstructure is defined as a compositionally and temperature-dependent polycrystalline aggregate mixture of CuInSe/sub 2/ and Cu/sub x/Se/In/sub y/Se minor phases at intragranular and grain boundary positions. The core crystallite exhibits order-disorder and a CuInSe/sub 2/-CuIn/sub 2/Se/sub 3.5/ phase separation and/or solid solution. The implications for device performance are dependent on the extent of band-bending and interface states at phase boundaries and on the filling extent of minor phase precipitates. The Cu-poor CuIn/sub 2/Se/sub 3.5/ phase may be suitable for device application.<>