Novel separation process for free-standing silicon thin-films

Reduction of the solar cell thickness decreases the material use and offers a mechanically flexible cell. The present contribution introduces a novel method to produce free-standing thin monocrystalline Si layers and solar cells. The method has three advantages over other methods: (i) The device layer is mechanically stable on the host wafer during device fabrication. (ii) Nevertheless, the separation of the layer is guaranteed after the device fabrication. (iii) No foreign substrate is necessary for the layer separation. The method is based on the locally defined formation of buried cavities only beneath the regions to be separated from the host wafer.