Lift-off of silicon epitaxial layers for solar cell applications

We have developed a technique which allows the fabrication of single crystalline layers of silicon of arbitrary size and shape and with a thickness ranging from less than 50 to greater than 100 μm. The films are grown by liquid phase epitaxy (LPE) on single crystal silicon substrates which have been patterned with a suitable masking layer material such as SiO₂. Detachment of the layers proceeds by etching through the regions where the epitaxial layer is attached to the substrate. In contrast to the technique utilized for the epitaxial liftoff of III-V compounds, this approach does not require an extremely selective etchant which etches a buffer layer while not attacking the epitaxial layer. The substrate can be re-used many times.