Rapid liftoff of epitaxial thin films

Electronic devices made from single crystal thin films attached to inexpensive support substrates offer reduced material costs compared to wafer-based devices; however, scalable and inexpensive processes for producing these single crystal film structures have remained elusive. In this work, we describe a new approach for fabricating these structures. In our approach, an epitaxial film is grown on a single crystal template and is then separated from its growth surface via fracture along a weak heteroepitaxial interface between the single crystal film and its growth substrate. We show that epitaxial films of Si, Ge, and GaAs, with thicknesses ranging from 100 nm to 1 μm, grown on epitaxial CaF2 overlayers on Si <111> substrates, can be transferred to glass substrates by inducing fracture along the heteroepitaxial interface between the semiconductor film and CaF2, or between CaF2 and the Si wafer, assisted by the presence of water as in moisture-assisted cracking.