InGaZnO Thin-film Transistors Research Articles

DC and AC Performance of InGaZnO Thin-Film Transistors on Flexible PEEK Substrate

DC and AC Performance of InGaZnO Thin-Film Transistors on Flexible PEEK Substrate

Strain-Sensor-In-Pixel Technology for Resolution-Sustainable Stretchable Displays.

One of the limitations of stretchable displays is the severe degradation of resolution or the decrease in the number of pixels per unit area when stretched. Hence, we suggest a strain-sensor-in-pixel (S-SIP) system through the adoption of hidden pixels that are activated only during the stretch mode for maintaining the density of on-state pixels. For the S-SIP system, the gate and source electrodes of InGaZnO thin-film transistors (TFTs) in an existing pixel are connected to a resistive strain sensor through the facile and selective deposition of silver nanowires (AgNWs) via electrohydrodynamic-jet-printing. With this approach, the strain sensor integrated TFT functions as a strain-triggered switch, which responds only to stretching along the designated axes by finely tuning the orientation and cycles of AgNW printing. The strain sensor-integrated TFT remains in an off-state when unstretched and switches to an on-state when stretched, exhibiting a large negative gauge factor of -1.1 × 1010 and a superior mechanical stability enduring 6000 cycles, which enables the efficient structure to operate hidden pixels without requiring additional signal processing. Furthermore, the stable operation of the S-SIP in a 5 × 5-pixel array is demonstrated via circuit simulation, implying the outstanding applicability and process compatibility to the conventional active-matrix display backplanes.

Effect of Oxygen Plasma Treatment on the Performance of GQDs-Modulated InGaZnO Thin-Film Transistors

Effect of Oxygen Plasma Treatment on the Performance of GQDs-Modulated InGaZnO Thin-Film Transistors

80‐4: Highly Reliable, As‐Grown Crystalline InGaZnO TFTs by Spray Pyrolysis for Low‐Cost Manufacturing of High‐Resolution AMOLED Display

We report a low‐cost method for growing highly‐oriented crystalline InGaZnO (C‐IGZO) for a high‐resolution, active‐matrix thin‐film transistor (TFT) backplane for organic light‐emitting diode displays using spray pyrolysis. The self‐aligned, coplanar oxide TFT with an as‐grown C‐IGZO channel layer demonstrates a threshold voltage of‐0.35 V, saturation mobility of 33.99 cm2 V‐1 s‐1 , and subthreshold swing of 0.15 Vdec‐1, with an on/off current ratio exceeding 108 . Moreover, the C‐IGZO TFT with a channel length of 1.16 μm exhibits excellent operational stability under bias temperature stress.

Analysis on charge-retention characteristics of sub-threshold synaptic IGZO thin-film transistors with defective gate oxides

We provide a quantitative analysis on the charge-retention characteristics of sub-threshold operating In–Ga–Zn–O (IGZO) thin-film transistors (TFTs) with a defective gate-oxide for low-power synaptic applications. Here, a defective SiO2 is incorporated as the synaptic gate-oxide in the fabricated IGZO TFTs, where a defect is physically playing the role as an electron trap. With this synaptic TFT, positive programming pulses for the electron trapping are applied to the gate electrode, followed by monitoring the retention characteristics as a function of time. And this set of the programming and retention-monitoring experiments is repeated in several times for accumulating effects of pre-synaptic stimulations. Due to these accumulated stimulations, electrons are expected to be getting occupied within a deeper trap-state with a higher activation energy, which can lead to a longer retention. To verify these phenomena, a stretched exponential function and respective inverse Laplace transform are employed to precisely estimate a retention time and trap activation-energy for transient experimental results.

Rational Design of Different Ga Content Bilayer InGaZnO Thin-Film Transistors With Al₂O₃/HfO₂ Passivation Layer

Rational Design of Different Ga Content Bilayer InGaZnO Thin-Film Transistors With Al₂O₃/HfO₂ Passivation Layer

Enhancing Reliability of Short-Channel Dual Gate InGaZnO Thin Film Transistors by Bottom-Gate Oxide Engineering

Enhancing Reliability of Short-Channel Dual Gate InGaZnO Thin Film Transistors by Bottom-Gate Oxide Engineering

Influence of RF power in the sputter deposition of amorphous InGaZnO film on the transient drain current of amorphous InGaZnO thin-film transistors

The device electrical and transient current characteristics of the amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs) are comprehensively investigated according to the radio-frequency (RF) power during the sputter-deposition of IGZO active film. The RF power dependencies of the oxygen vacancy (VO) concentration in IGZO and the surface morphology of IGZO film are analyzed through X-ray photoelectron spectroscopy (XPS) and atomic force microscope (AFM). According to the RF power change in the range of 100 ∼ 250 W, the optimal point in terms of threshold voltage (VT), ON current (Ion), field-effect mobility in the linear region (μFE_lin), hysteresis voltage (VHys), and the VT shift under current stress (ΔVT) is found to be 200 W. The existence of the optimal power condition originates from the RF-power dependencies of the electron carrier concentration, the density of electron traps in gate insulator (GI), and the interface trap density related to surface roughness.Furthermore, compared to the direct current (DC) current stress (CS) condition, it is found that when VGS rises rapidly, a total transient current ΔID can be decomposed into three components, i.e., ΔIOS, ΔIBOOST, ΔIDEG. While ΔIOS is attributed to the non-quasi static Fermi-level rising, ΔIBOOST and ΔIDEG result from the donor creation in IGZO and the electron trapping into GI and interface. Noticeably, the occurrence level of each component changes sensitively according to RF power.Our result suggests that the 200 W device has the least overshoot of transient current and shows the best reliability in terms of deterioration due to transient current characteristics.

Output breakdown characteristics of amorphous InGaZnO thin-film transistors at high gate voltage

Output characteristics of top-gate amorphous InGaZnO thin-film transistors are investigated at high gate voltage. With the increasing drain voltage, an output breakdown crops up closely following a drastic uprush of drain current. Such dramatically elevated drain current derives from the self-heating (SH) effect-generated channel donors. Measured at different high gate voltages, the output breakdown occurs in either linear or saturation regime, respectively, corresponding to normally-on and normally-off transfer curve, while the SH-triggering powers are almost identical. The conductor-like channel originates from the SH-induced high donor population, while the disconnection between channel and drain is caused by a highly defective region near drain, where the hot-carrier damage is violently activated by the SH-induced high temperature and the high drain electric field in saturation regime.

Control of Interfacial Defect States in the Flexible InGaZnO Thin Film Transistor with a 6FDA-MDA Gate Insulator by Using an Al2O3 Interlayer

Control of Interfacial Defect States in the Flexible InGaZnO Thin Film Transistor with a 6FDA-MDA Gate Insulator by Using an Al₂O₃ Interlayer

Bi-directional threshold voltage shift of amorphous InGaZnO thin film transistors under alternating bias stress

Amorphous InGaZnO (a-IGZO) has attracted a lot of attention as a high-mobility channel material for thin film transistors (TFTs). However, the instability mechanism involving threshold voltage and subthreshold swing (SS) in a-IGZO TFTs still requires further investigation. In this study, we investigated the electrical instability of amorphous InGaZnO TFTs subjected to alternating positive and negative bias stresses. Based on the respective mechanisms under positive and negative bias stresses, including ionization and spatial movement of oxygen vacancies, bi-directional threshold voltage shifts were observed under alternating bias stress. The SS values vary with the bias stress polarity, reflecting the presence and distribution of oxygen vacancies. Our findings reveal a complementary mechanism based on oxygen vacancies, elucidating the behavior under complex bias stress schemes and extending our understanding of instability mechanisms beyond monotonous bias stress.

Reduction of internal stress in InGaZnO (IGZO) thin film transistors by ultra-thin metal oxide layer

In this study, the modification of indium gallium zinc oxide (IGZO) thin-film transistors (TFTs) with an ultrathin metal oxide layer successfully reduces internal film stress. The introduction of an Al2O3 metal oxide layer effectively diminishes defects within the film and minimizes distortion in the film densification process. A low-temperature annealing process at 200 °C was employed to mitigate thermal expansion differences between the film and the substrate, thus reducing internal stress within the device. Furthermore, we have discovered that this structural modification holds the potential to enhance mechanical stress resistance. This paper offers a novel perspective and an experimental foundation for the stress analysis of flexible TFTs.

Solution-processed bilayer InGaZnO/In2O3 thin film transistors at low temperature by lightwave annealing

At low temperatures about 230 °C, bilayer InGaZnO/In2O3 thin film transistors (TFTs) were prepared by a solution process with lightwave annealing. The InGaZnO/In2O3 bilayer TFTs with SiO2 as dielectric layer show high electrical performances, such as a mobility of 7.63 cm2V−1s−1, a threshold voltage (V th) of 3.8 V, and an on/off ratio higher than 107, which are superior to single-layer InGaZnO TFTs or In2O3 TFTs. Moreover, bilayer InGaZnO/In2O3 TFTs demonstrated a great bias stability enhancement due to the introduction of top InGaZnO film act as a passivation layer, which could prevent the interaction of ambient air with the bottom In2O3 layer. By using high dielectric constant AlO x film, the InGaZnO/In2O3 TFTs exhibit an improved mobility of 47.7 cm2V−1s−1. The excellent electrical performance of the solution-based InGaZnO/In2O3 TFTs shows great application potential for low-cost flexible printed electronics.

Ultrasonic Treatment-Induced Enhancement of Mechanical and Electrical Properties in InGaZnO Thin-Film Transistors

Ultrasonic Treatment-Induced Enhancement of Mechanical and Electrical Properties in InGaZnO Thin-Film Transistors

The Endurance and Reliability Mechanisms Investigation of InGaZnO and InSnO Thin Film Transistors

The Endurance and Reliability Mechanisms Investigation of InGaZnO and InSnO Thin Film Transistors

Increased Threshold Voltage of Amorphous InGaZnO Thin-Film Transistors After Negative Bias Illumination Stress

Increased Threshold Voltage of Amorphous InGaZnO Thin-Film Transistors After Negative Bias Illumination Stress

Self-Aligned InGaZnO Thin-Film Transistors and Circuits on Transparent Thin Glass and FEP Film

Self-Aligned InGaZnO Thin-Film Transistors and Circuits on Transparent Thin Glass and FEP Film

Control of hydrogen concentration on InGaZnO thin film using cryopumping system

Amorphous InGaZnO thin film transistors (a-IGZO TFTs) have been extensively studied as driving transistors for large organic light emitting diode (OLED) displays due to its’ exceptional uniformity. However, the positive bias stability (PBS) of a-IGZO TFT is not sufficiently acceptable to endure the long on-stress time. Here, the effect of hydrogen impurities in a-IGZO channels on the stability and performance of TFTs used in OLED displays are investigated. The hydrogen content in the a-IGZO film is reduced to limit the formation of trapping sites for charge carriers and improve TFT stability. This study uses a cryogenic pumping system to reduce the hydrogen impurity density during the deposition process and examines the electrical characteristics of bottom-gate a-IGZO TFTs. The threshold voltage shift (ΔVth) of the a-IGZO TFT fabricated using the cryogenic pumping system was found to be reduced by 3.4–6.9 V, compared to the TFT fabricated using the turbo molecular pump system. The hydrogen and oxygen concentrations in the oxide thin films are quantitatively analyzed, and the mechanism of OH bonding acting as an electron trap during positive bias stress is explained. Overall, this study provides insights into the impact of hydrogen impurities in a-IGZO TFT stability and performance, as well as proposes a method using cryopump for reducing hydrogen impurities to improve OLED display reliability.

Low temperature plasma deposited SiO2/organosilicon stacked film for transparent gate dielectric of InGaZnO thin film transistor

In this article, a 5-pair SiO2/organosilicon stacked film fabricated by inductively coupled plasma-enhanced chemical vapor deposition from hexamethyldisiloxane /O2 at low temperature was introduced as InGaZnO thin film transistor (IGZO TFT) gate dielectric for transparent flexible displays. The dielectric film has the flexibility of organosilicon while maintaining the high dielectric strength of SiO2. Due to the introduction of organosilicon, which connects with the IGZO active layer, the deep-state electron traps formed by oxygen vacancies are reduced, and moderate hydrogen diffused into IGZO layer becomes a shallow donor. Under the premise of high transmittance of the dielectric film, a high-performance TFT with mobility of 15.60 cm2/Vs was obtained.

Solution-Processed Aluminum-Zirconium Oxide as a Gate Dielectric for InGaZnO Thin Film Transistors

Solution-Processed Aluminum-Zirconium Oxide as a Gate Dielectric for InGaZnO Thin Film Transistors