A printable form of silicon for high performance thin film transistors on plastic substrates

Free-standing micro- and nanoscale objects of single crystal silicon can be fabricated from silicon-on-insulator wafers by lithographic patterning of resist, etching of the exposed top silicon, and removing the underlying $\mathrm{Si}{\mathrm{O}}_2$ to lift-off the remaining silicon. A large collection of such objects constitutes a type of material that can be deposited and patterned, by dry transfer printing or solution casting, onto plastic substrates to yield mechanically flexible thin film transistors that have excellent electrical properties. Effective mobilities of devices built with this material, which we refer to as microstructured silicon $\left(\mu \mathrm{s}\text{-}\mathrm{Si}\right)$ , are demonstrated to be as high as $180{\mathrm{cm}}^2∕\mathrm{V}\mathrm{s}$ on plastic substrates. This form of “top down” microtechnology might represent an attractive route to high performance flexible electronic systems.