Dresden 2006 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 32: Photovoltaic

HL 32.2: Vortrag

Mittwoch, 29. März 2006, 14:45–15:00, BEY 118

Ga incorporation into CuInS₂ solar cell absorbers fast sulfurization processes — •Roland Mainz and Reiner Klenk — Hahn-Meitner-Institut, Glienicker Strasse 100, 14109 Berlin, Germany

It has been shown previously, that the performance of CuInS2-based (CIS) solar cells can be improved by incorporation of Ga into the absorber [1]. Industrial production requires a cheap and fast preparation method such as sulfurization of sputtered metal precursor films in a rapid thermal processor (RTP). This works well for pure CuInS₂ but various problems have been encountered with this particular preparation method after adding gallium to the precursor. We have therefore studied the influence of gallium on phase formation by in-situ energy dispersive x-ray diffraction (XRD) using synchrotron radiation. Results indicate that the phase formation sequence during sulfurization strongly depends on the layer sequence in the precursor as well as on the time dependence of the sulphur pressure in the reaction chamber. The information gained from these experiments is used to establish a process that works within the constraints imposed by the industrial application. Furthermore, results indicate that it is possible to influence the depth profile of the Ga in the film. Partial replacement of In by Ga increases the band gap of CuInS₂. Control over the Ga depth profile allows the implementation of an optimum (in terms of solar cell performance) band gap grading.

[1] R. Kaigawa A. Neisser R. Klenk M. Ch. Lux-Steiner. Improved performance of thin film solar cells based on Cu(In,Ga)S₂. Thin Solid Films, page 415 pp., 2002.