Bendable single crystal silicon thin film transistors formed by printing on plastic substrates

Bendable, high performance single crystal silicon transistors have been formed on plastic substrates using an efficient dry transfer printing technique. In these devices, free standing single silicon objects, which we refer to as microstructured silicon (μs-Si), are picked up, using a conformable rubber stamp, from the top surface of a wafer from which they are generated. The μs-Si is then transferred, to a specific location and with a controlled orientation, onto a thin plastic sheet. The efficiency of this method is demonstrated by the fabrication of an array of thin film transistors that exhibit excellent electrical properties: average device effective mobilities, evaluated in the linear regime, of ∼240 cm ²/V s, and threshold voltages near 0 V. Frontward and backward bending tests demonstrate the mechanical robustness and flexibility of the devices.