Phase constitution and element distribution in Cu-In-S based absorber layers grown by the CISCuT-process

Solar cells based on CISCuT grown Cu-In-S absorber layers obtained efficien cies of about 6% in small areas. The CISCuT process for Cu-In-S absorber la yer preparation starts from an metallurgical grade Cu tape. On this tape a thin In layer is electrochemically deposited in a continuous roll to roll p rocess. The following sulphurisation step - also in a continuous roll to ro ll process - is characterised by a short reaction time of a few seconds and a relatively high process temperature of about 600 degrees C under normal pressure in N-2 atmosphere. Special conditions in the sulphurisation proces s lead to a well defined layer sequence of different Cu-In-S phases inside the grown layer. X-ray diffraction (XRD) based quantitative phase analysis of KCN etched CISCuT absorber layers shows the phases CuInS2, CuIn5S8 and C u/In delta-phase. The measurements correspond to transmission electronic mi croscopy (TEM) and energy dispersive analysis of X-rays (EDX) determined ph ase constitutions and sublayer thickness. Additional investigations with RA MAN-spectroscopy as well as secondary ion mass spectrometry (SIMS) and seco ndary neutrals mass spectrometry (SNMS) give a consistent idea of the layer sequences and the impurity distribution inside the film system. As far as we know we describe here, for the first time, such an absorber structure po ssibly with advantages for further solar cell developments. (C) 2000 Elsevi er Science S.A. All rights reserved.