[13p-4F-1~9] Science and recent trend of liquid silicon

[13p-4F-8] Solution-processed polycrystalline silicon on paper

〇Ryoichi Ishihara^1,2, Miki Trifunovic¹, Jin Zhang¹, Tatsuya Shimoda² (1.Delft Univ. Technol., 2.JAIST)

Keywords:Silicon,printing,solution

Solution process has received many attentions in recent years because of low-cost manufacturability of flexible electronic devices owing to the additive process. Organic and metal-oxide semiconductors can be printed at low temperature however carrier mobility and reliability of TFTs using those materials are still far lower than those for silicon. Silicon as the base material, on the other hand, has advantages in terms of high mobilities, stability, knowledge of the material, and low-power consumption by CMOS circuit configuration. Silicon can be printed using a liquid silicon ink, which is a mixture of polymerized cyclopentasilane (CPS) and a solvent. A thermal annealing higher than 350^oC of this material, however, was necessary, to convert it to solid silicon which prevented its usage on inexpensive substrates with a limited thermal budget. In this work, we introduce a method that allows polycrystalline silicon (poly-Si) formation on paper directly from the same liquid silicon ink using docter-blade coating and excimer laser irradiation with maximum temperature of 80^oC. Using the same method, poly-Si TFTs were fabricated and electron and hole mobilities of 21.0 cm²/Vs and 23.5 cm²/Vs, respectively, were obtained, which are higher than the solution processed conventional organic and metal oxide TFTs. This technique will be attractive, not only for alternative material for printed electronics in general, but also for applications such as fast printed electronics with silicon circuits integrated on paper, which is inexpensive, recyclable, biodegradable and even edible.