摘要
Printing of electronics is pursued as a low-cost alternative to conventional manufacturing processes.In addition,owing to relatively low process temperatures,flexible substrates can be used enabling novel applications.Among flexible substrates,paper was found to be a particularly interesting candidate,since it has an order of magnitude lower price than low-cost polymer alternatives,and is biodegradable.As ink materials,organic and metal-oxide semiconductors are thoroughly being investigated;however,they lack in electric performance compared to silicon in terms of device mobility,reliability,and energy efficiency.In recent years,liquid precursors for silicon were found and used to create polycrystalline silicon(poly-Si).However,fabrication of transistors on top of low-cost flexible substrates such as paper has remained an outstanding challenge.Here we demonstrate both p-channel and nchannel poly-Si thin-film transistors(TFTs)fabricated directly on top of paper with field-effect mobilities of 6.2 and 2.0 cm2/V s,respectively.Many fabrication challenges have been overcome by limiting the maximum process temperature to approximately 100℃,and avoiding liquid chemicals commonly used for etching and cleaning.Patterning of poly-Si has been achieved by additive selective crystallization of the precursor film using an excimer laser.This work serves as a proof of concept,and has the potential to further improve device performance.Owing to the low-cost,biodegradable nature of paper,and the high performance,reliability,and energy efficiency of poly-Si TFTs,this work opens a pathway toward truly low-cost,low-power,recyclable applications including smart packages,biodegradable health monitoring units,flexible displays,and disposable sensor nodes.
