Si microwires based FETs on flexible substrates

This paper presents the new route for fabricating field effect transistors (FETs) on flexible or bendable substrates using a combination of transfer printing and screen printing technologies - the former is used to transfer single crystal silicon (Si) microwires on to flexible substrate and the latter to print the metal lines. A back-gated FET structure has been realized with screen printed silver (Ag) lines as the gate electrode and the transfer-printed arrays of Si microwires are utilized as semiconductor layers of the device. Epoxy based negative resist SU-8 has been used as the adhesive as well as the dielectric for the FET device. An array of 20 wires with variable widths and lengths was developed by using standard photolithography and etching techniques. A custom made micro-spotting technique has been used to obtain the source and drain contacts on top of Si microwires. Good mechanical and electrical responses of the FETs have been observed during the cyclic tests and current-voltage (I-V) measurements respectively.