Mechanically Flexible and High-Performance CMOS Logic Circuits

Abstract

Low-power flexible logic circuits are key components required by the next generation of flexible electronic devices. For stable device operation, such components require a high degree of mechanical flexibility and reliability. Here, the mechanical properties of low-power flexible complementary metal–oxide–semiconductor (CMOS) logic circuits including inverter, NAND, and NOR are investigated. To fabricate CMOS circuits on flexible polyimide substrates, carbon nanotube (CNT) network films are used for p-type transistors, whereas amorphous InGaZnO films are used for the n-type transistors. The power consumption and voltage gain of CMOS inverters are <500 pW/mm at Vin = 0 V (<7.5 nW/mm at Vin = 5 V) and >45, respectively. Importantly, bending of the substrate is not found to cause significant changes in the device characteristics. This is also observed to be the case for more complex flexible NAND and NOR logic circuits for bending states with a curvature radius of 2.6 mm. The mechanical stability of these CMOS logic circuits makes them ideal candidates for use in flexible integrated devices.

Metal oxide semiconductor thin-film transistors for flexible electronics

“…51). 103 344 The SWCNT/IGZO NOT gate shows a gain of 45 V/V and a low t r ¼ 0.75 ms. 344 The same group also realized 3D vertically integrated SWCNT/IGZO NOT gates with similar performance. Based on the previously mentioned 3D vertically integrated SWCNT/IGZO TFT structure shown by Honda et al, common-source amplifiers with a gain G > 5 dB have also been fabricated.…”

“…272 Li et al recently demonstrated a flexible 5-stage ring oscillator based on n-type ZnO TFTs and p-type SnO x TFTs, with a maximum oscillation frequency of 18.4 kHz. 177 Recently, solution-processed semiconducting SWCNTs have also been exploited as p-type TFTs 345 and integrated into flexible complementary circuits with n-type sputtered IGZO 103,332,343,344 or spray coated In 2 O 3 TFTs. 145 Bendable hybrid SWCNT/IGZO NOT gates on PI show a maximum gain of 87 V/V, a nearly perfectly centered V M , and a "rail-to-rail" V L (Fig.…”

“…Several groups 103,172,177,330,343,344 have characterized hybrid complementary NOT gates under tensile bending, down to radii of 2.6 mm ( ¼ 1.25%), 343 showing only minor variations. Oh et al reported mechanical bending tests of pentacene/ZnO NOT gates at bending radii of 56 mm with high gains of 100 V/V.…”

“…and dip-coating, 332,343,344 in addition to the widely used thermal evaporation with shadow masking. 172,330,331,340 Different groups have so far demonstrated the potential of integrating p-type pentacene, 172,330,331,340 poly-(9,9-dioctylfluorene-co-bithiophene) (F8T2), 341,342 and semiconducting single walled carbon nanotubes (SWCNTs) 342 The F8T2/IGZO NOT gate shows a gain G ¼ 100 V/V at a maximum supply of 30 V. 342 The same group realized also vertically stacked F8T2/IGZO NAND gates on PET.…”

All‐Carbon Thin‐Film Transistors as a Step Towards Flexible and Transparent Electronics

“…It is desirable to convert major carrier types by a doping strategy to obtain n-type transfer characteristics, and further build up CMOS configuration, which is a requirement for realistic all-carbon logic circuits, because CMOS devices have the merits of a higher noise immunity and a lower static power consumption. [226,[228][229][230] All-carbon flexible and transparent TFTs will contribute not only to next-generation display applications but also to novel gas and biological sensors, optical detectors, radio-frequency identification tags and internet-of-things applications. [219,231] These new types of electronics allow integration of sensing, display, and interactive functionalities on a single chip.…”