Highly Stable Indium‐Gallium‐Zinc‐Oxide Thin‐Film Transistors on Deformable Softening Polymer Substrates

Abstract

more complex applications that more closely mimic the behavior and size scale of biology. To these ends, bioelectronic devices must demonstrate several critical features: be manufacturable via a repeatable fabrication processes; exhibit resistance to mechanical deformation; and demonstrate electrical reliability.Technologies based on TFTs allowed the microfabrication of large-area applications such as flat-panel displays, which were difficult to develop on flexible substrates due to their high temperature processing requirements and were difficult to develop on silicon due to the cost associated with using such a large area of silicon. After Nomura et al. presented TFTs based on indium-gallium-zinc-oxide (IGZO) semiconductors, these became the key component for the fabrication of system-on-glass applications. [9] The electrical performance of IGZO TFTs exhibited high-mobility values (>10 cm 2 V −1 s −1 ) compared with organic semiconductors (<0.1 cm 2 V −1 s −1 ) or amorphous silicon (≈1 cm 2 V −1 s −1 ). [9][10][11] More recently, IGZO has been reported with mobility values of 29 cm 2 V −1 s −1 by Jeon et al. to develop a voltage compensation circuit. [12] A transparent circuit based on IGZO TFTs with mobility of 70 cm 2 V −1 s −1 was presented by Liu et al. with frequency response on the order of megahertz. [13] In addition, Liu et al. incorporated silver nanowires into IGZO to achieve a mobility of 174 cm 2 V −1 s −1 , [14] but with limits on processing and scalability. Due to their relative low processing temperature requirements (compared with silicon technologies) and high-mobility, semiconductor devices made from IGZO allow for the development of emerging technologies such as flexible and wearable electronics: active-matrix phosphorescent organic light emitting diodes displays by O'Brien et al., [15] an amplifier by Münzenrieder et al., [16] and a full color organic light-emitting diodes (OLED)-based display [4] among others.There is a tradeoff among the various processing temperatures used during TFT fabrication, which affects electrical performance and the thermal compatibility with flexible substrates. Important performance characteristics of the electronic components include field effect mobility (μ FE ), threshold voltage (V TH ), changes in V TH (ΔV TH ), and subthreshold swing (SS). The use of elevated temperature during device processing can help improve the quality of amorphous IGZO, as well as its interface with a dielectric. According to Nomura, Flexible electronics are attracting great interest in healthcare, where devices such as thin-film transistors (TFTs) on polymer substrates facilitate biomedical applications requiring complex circuits in soft packages. Consequently, a repeatable process to fabricate reliable, stable electronic components on flexible substrates is required. Here, thermoset thiol-ene/acrylate shape memory polymer (SMP) substrates house indium-gallium-zinc-oxide (IGZO) TFTs and logic circuits: resulting devices exhibit stable behavior after thermal annealing at 250 °C. Fabr...

A Review: Electrode and Packaging Materials for Neurophysiology Recording Implants

“…The electrode showed at least 10× reduction in electrochemical impedance, ~7% transmittance improvement, and stability after over 600 cycles of mechanical bending (Yang et al, 2019b ). Other semiconducting materials, such as germanium (Ge), silicon germanium alloy (SiGe), indium-doped zinc oxide (IZO), indium-gallium-zinc oxide (a-IGZO), and zinc oxide (ZnO), has also been investigated as recording electrode materials because of their desired electrical, mechanical, optical, biocompatible, and stable/biodegradable properties (Gao et al, 2012 ; Dagdeviren et al, 2013 ; Lee et al, 2015 ; Gutierrez-Heredia et al, 2017 ; Mao et al, 2018 ; Huerta et al, 2019 ).…”

Indium–Gallium–Zinc Oxide Schottky Diodes Operating across the Glass Transition of Stimuli‐Responsive Polymers

“…A previous study demonstrated that even with a 5 µm thick polymer encapsulation layer, IGZO thin-film transistors fabricated on the same softening polymer substrate endured bending stresses up to 10 000 cycles. [22] Finally, the high-frequency properties of the Schottky diodes were characterized by one-port scattering parameter measurements. Figure 6a shows representative impedance spectra obtained from a 100 µm × 100 µm Schottky diode fabricated on the softening polymer substrate, demonstrating a cutoff frequency (f c ) of ≈1 GHz at 0 V bias.…”

Top-Gate Short Channel Amorphous Indium-Gallium-Zinc-Oxide Thin Film Transistors With Sub-1.2 nm Equivalent Oxide Thickness

“…morphous oxide semiconductor TFTs, due to their moderate mobility, low cost, large size uniformity, high transparency, and excellent flexibility, have been widely used in applications from large-scale display to flexible portable devices [1][2][3][4][5][6][7][8][9][10][11][12][13]. In addition, because of a low process temperature and extremely low off-state current (I off ), they have tremendous promise in emerging applications, including internet of things (IoT), monolithic three-dimensional (3D) integrated nano-electronic, and photonic systems [14][15][16][17], where low power and high performance are highly desired.…”