Ge2Sb2Te5 p-Type Thin-Film Transistors on Flexible Plastic Foil
Electronics Laboratory, Department of Information Technology and Electrical Engineering, 8092 Zürich, Switzerland
Author to whom correspondence should be addressed.
Received: 27 July 2018 / Revised: 26 August 2018 / Accepted: 7 September 2018 / Published: 9 September 2018
In this work, we show the performance improvement of p-type thin-film transistors (TFTs) with Ge
(GST) semiconductor layers on flexible polyimide substrates, achieved by downscaling of the GST thickness. Prior works on GST TFTs have typically shown poor current modulation capabilities with ON/OFF ratios ≤20 and non-saturating output characteristics. By reducing the GST thickness to 5 nm, we achieve ON/OFF ratios up to ≈300 and a channel pinch-off leading to drain current saturation. We compare the GST TFTs in their amorphous (as deposited) state and in their crystalline (annealed at 200 °C) state. The highest effective field-effect mobility of 6.7 cm
/Vs is achieved for 10-nm-thick crystalline GST TFTs, which have an ON/OFF ratio of ≈16. The highest effective field-effect mobility in amorphous GST TFTs is 0.04 cm
/Vs, which is obtained in devices with a GST thickness of 5 nm. The devices remain fully operational upon bending to a radius of 6 mm. Furthermore, we find that the TFTs with amorphous channels are more sensitive to bias stress than the ones with crystallized channels. These results show that GST semiconductors are compatible with flexible electronics technology, where high-performance p-type TFTs are strongly needed for the realization of hybrid complementary metal-oxide-semiconductor (CMOS) technology in conjunction with popular n-type oxide semiconductor materials.
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MDPI and ACS Style
Daus, A.; Han, S.; Knobelspies, S.; Cantarella, G.; Tröster, G. Ge2Sb2Te5 p-Type Thin-Film Transistors on Flexible Plastic Foil. Materials 2018, 11, 1672.
Daus A, Han S, Knobelspies S, Cantarella G, Tröster G. Ge2Sb2Te5 p-Type Thin-Film Transistors on Flexible Plastic Foil. Materials. 2018; 11(9):1672.
Daus, Alwin; Han, Songyi; Knobelspies, Stefan; Cantarella, Giuseppe; Tröster, Gerhard. 2018. "Ge2Sb2Te5 p-Type Thin-Film Transistors on Flexible Plastic Foil." Materials 11, no. 9: 1672.
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