High-speed strained-single-crystal-silicon thin-film transistors on flexible polymers

We fabricate thin-film transistors (TFTs) on both strained and unstrained single-crystal Si membranes transferred to flexible-polymer substrates. The active layer is transferred from the starting silicon on insulator (SOI) using a simple, fast, and reliable dry-printing method. When a multilayer Si∕SiGe∕Si structure is pseudomorphically grown on SOI and the buried oxide is selectively removed, strained Si with a negligible density of dislocations is achieved via elastic strain sharing between the SiGe alloy layer and the Si layers. Both the drain current and the transconductance of TFTs fabricated on this strained Si∕SiGe∕Si membrane after its transfer to the flexible polymer are much higher than of TFTs fabricated on the unstrained-Si counterpart.