Flexible electronics: 12-GHz Thin-Film Transistors on Transferrable Silicon Nanomembranes for High-Performance Flexible Electronics (Small 22/2010)

Multigigahertz flexible electronics are attractive and have broad applications. A gate‐after‐source/drain fabrication process using preselectively doped single‐crystal silicon nanomembranes (SiNM) is an effective approach to realizing high device speed. However, further downscaling this approach has become difficult in lithography alignment. In this full paper, a local alignment scheme in combination with more accurate SiNM transfer measures for minimizing alignment errors is reported. By realizing 1 μm channel alignment for the SiNMs on a soft plastic substrate, thin‐film transistors with a record speed of 12 GHz maximum oscillation frequency are demonstrated. These results indicate the great potential of properly processed SiNMs for high‐performance flexible electronics. The cover picture shows 12‐GHz thin‐film transistor (TFT) arrays integrated with radio‐frequency (RF) passive elements (inductors and capacitors) on a bendable polyethylene terephthalate plastic substrate. Monocrystalline silicon nanomembranes, which are preselectively doped to transform the high carrier mobility into high device speed, are released from the silicon‐oninsulator and directly flip‐transferred (top right) to the low‐thermal‐budget plastic substrate with high fidelity registration. Local alignment enables the fabrication of very fine device features on the soft plastic substrate (lower left) for miniaturized TFTs. With the record speed, the application of flexible electronics will be dramatically expanded. RF and wireless device applications that could previously only be addressed by rigid‐chip‐based electronics can now be readily addressed by flexible electronics. For more information, please read the Full Paper “12‐GHz Thin‐Film Transistors on Transferrable Silicon Nanomembranes for High‐Performance Flexible Electronics”by Z. Ma and co‐workers beginning on page 2553.