Spectral photoluminescence measurements for in-line absorber characterization in thin-film production lines

The cell efficiency of CIGS thin-film modules is highly influenced by the composition of the absorber layer. An in line monitoring of the absorber composition within the production process should hence be of fundamental interest to assure a constantly high quality of produced modules, to correct drifts within the production as soon as they occur and to identify rejects immediately. We have developed an optical system measuring photoluminescence (PL) spectra in thin-film production processes. Applications for this technique are in-line composition monitoring in CIGS layers and band-gap determination in CdTe and CdS layers.