Robust Oxide Thin-Film Transistors With Embedded CNT Buried Layer for Stretchable Electronics

Abstract

We report the impact of carbon nanotube (CNT) buried layer in the middle of 7 μm polyimide (PI) substrate on the electrical performance of amorphous-indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs) by repetitive mechanical stretching. TFT arrays on 3 mm × 3 mm PI layers were attached on 40 μm polydimethylsiloxane (PDMS) substrate by double-sided PI tape. A negative threshold voltage shift (V Th (V)) of −3 V has been found under 70% mechanical stretching for the TFTs on the conventional PI substrate, whereas the TFTs with CNT layer inside PI substrate exhibited robust TFT performance. The fabricated oxide TFTs reported here with CNT inside PI substrate shows field effect mobility (μ FE) ∼ 14 cm 2 /V • s at pristine state, and changed <5% after repetitive mechanical stretching and bending which might be attributed from the strain absorbing CNT layer inside PI substrate using TCAD simulation.

Biaxially Stretchable Active‐Matrix Micro‐LED Display with Liquid Metal Interconnects

“…The detailed fabrication process of the oxide TFTs backplane is explained in detail in the experimental section and previous works. [54][55][56] From the backplane to micro-LED bonding, additional processes are shown, including solder patterning, micro-LED bonding, and passivation (Figure S1, Supporting Information). The detailed schematic illustration and optical image for each step can be shown in Figure S1a-d (Supporting Information).…”

High density integration of stretchable inorganic thin film transistors with excellent performance and reliability

“…Stretchable electronics using oxide TFTs also have been steadily reported so far, and we surveyed these studies with emphasis on three main figure of merits, including field effect mobility, stretchability, and device density (Supplementary Table 1) 17,19,[30][31][32][33][34][35][36][37][38][39] . Among the reports on stretchable oxide TFT arrays, Kim et al recently reported stretchable a-IGZO TFT with quite high mobility of 24.9 cm 2 V −1 s −1 , but it can be stretched only up to 30% and just four devices are placed on a substrate size of 25 × 25 mm 2 39 .…”

Highly Scalable and Robust Mesa‐Island‐Structure Metal‐Oxide Thin‐Film Transistors and Integrated Circuits Enabled by Stress‐Diffusive Manipulation

“…[ 25 ] Additionally, too thin PI substrates were known to obtain free‐standing and wrinkle‐free PI substrate without additional buried layer acting as the mechanical backbone. [ 26 ] Despite highly stable electronics were achieved on ultrathin PI films (<3 µm), unexpected air bubble was observed after detachment from carrier glass and consecutive attachment for measurement. [ 27 ] In these reasons, suitable thickness of flexible substrate is essential for practical use.…”

“…Stretchable electronics were demonstrated based on a PI/PDMS substrate. [ 26,29 ] In this study, stiff PI islands were additionally formed on the PDMS substrate where the strain can be reduced compared to the PI‐free PDMS regions. In spite of its unique substrate structure effectively relieving the stress, the use of an elastomeric PDMS substrate can be detrimental for realizing commercial‐level large‐area electronics.…”