Novel intermediate reflector layer for optical and morphological tuning in the Micromorph thin film tandem cell

PECVD growth of the microcrystalline silicon junction on a highly textured amorphous top cell often leads to defective absorber layers and finally to low quality bottom cell. This paper reports on the current status of using an innovative smoothening/reflective layer (SRL) as alternative intermediate reflector between top and bottom cell of a Micromorph tandem device deposited on as-grown highly textured LPCVD ZnO layer. Manufacturing of the SRL layer is realized by “liquid phase” deposition technologies. Optical and electrical properties, smoothening effect and photoelectrical results of Micromorph tandem devices are discussed. The implementation of our novel SRL results in the growth of a crack-free bottom cell and to an efficient current transfer from the bottom to the top cell.