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We demonstrate high‐performance coplanar thin film transistors (TFTs) on polyimide (PI) substrate, with very thin polycrystalline InGaO (poly‐IGO) thin films deposited by spray‐pyrolysis. The TFTs exhibit saturation mobility (µSAT) of ~39.25 ± 0.73 cm2 V−1 s−1, with excellent uniformity and stable bias stabilities (ΔVTH = +0.3 V for PBTS, ΔVTH = −0.3 V for NBTS). The 7‐stage ring oscillator made of the corresponding TFTs exhibits a very high oscillation frequency of 9.09 MHz at VDD of 15 V with ultra‐low propagation delay time of 7.86 ns/stage. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

We report complementary metal‐oxide semiconductor (CMOS)‐compatible, negative capacitance (NC) ferroelectric (FE) zirconium‐aluminum oxide (ZAO)/ZnO thin‐film transistors (TFTs) at a low thermal budget of 360 °C. The NC‐FE‐TFTs demonstrate uniform device‐to‐device performances, featuring a high memory window of 6.7 ± 0.1 V and steep subthreshold swing of 43 ± 4 mV dec–1. The observation of negative differential resistance at room temperature confirms the NC effect in FE‐ZAO/ZnO TFTs. In addition, a learning accuracy of ≈92% is achieved, highlighting the potential for high precision neuromorphic computing application. [ABSTRACT FROM AUTHOR]

Here, we report the high-performance amorphous gallium indium tin oxide (a-IGTO) thin-film transistor (TFT) with zirconium aluminum oxide (ZAO) gate insulator by spray pyrolysis. The Ga ratio in the IGTO precursor solution varied up to 20%. The spray pyrolyzed a-IGTO with a high-k ZAO gate insulator (GI) exhibits the field-effect mobility (μFE) of 16 cm2V−1s−1, threshold voltage (VTH) of −0.45 V subthreshold swing (SS) of 133 mV/dec., and ON/OFF current ratio of ~108. The optimal a-IGTO TFT shows excellent stability under positive-bias-temperature stress (PBTS) with a small ΔVTH shift of 0.35 V. The enhancements are due to the high film quality and fewer interfacial traps at the a-IGTO/ZAO interface. Therefore, the spray pyrolyzed a-IGTO TFT can be a promising candidate for flexible TFT in the next-generation display. [ABSTRACT FROM AUTHOR]

High‐performance, spray‐pyrolyzed amorphous indium‐gallium‐zinc oxide (a‐IGZO) thin‐film transistor (TFT) with self‐aligned (SA) coplanar structure is demonstrated. The spray‐pyrolyzed a‐IGZO film exhibits bubbles‐free smooth surface roughness (0.81 nm) and low oxygen‐related defects (22.5%). The fluorine‐doped a‐IGZO film shows a low resistivity of 1.18 × 10−3 Ω‐cm by NF3 plasma treatment. This is sufficient to obtain ohmic contact with the source/drain electrodes and doped IGZO in the offset region of the SA coplanar TFT. The spray‐pyrolyzed a‐IGZO TFT exhibits the field‐effect mobility (µFE) of 18.17 cm2 V−1 s−1, the threshold voltage (VTH) of −1.52 V, the subthreshold swing (SS) of 0.266 V dec−1, and a high on/off current ratio (Ion/Ioff) over 108 with a very low gate leakage current (<10−13 A). The hysteresis‐free and highly stable performances are achieved due to the excellent a‐IGZO channel and SiO2 gate insulator interface. A twenty‐three‐stage ring oscillator is demonstrated with SA coplanar TFTs, exhibiting a high oscillation frequency of 2.66 MHz and a low propagation delay of 8.17 ns/stage. Therefore, the spray‐pyrolyzed a‐IGZO film can be a promising metal oxide semiconductor for high‐performance TFTs backplane in large areas and high‐resolution display applications. [ABSTRACT FROM AUTHOR]

A stack passivation by spray pyrolysis is demonstrated for high performance and stable amorphous indium‐gallium‐zinc‐oxide (a‐IGZO) thin‐film transistors (TFTs). The device performances and stabilities of a‐IGZO TFTs are compared with single zirconium‐aluminium‐oxide (ZAO), aluminium oxide (Al2O3), and stack ZAO/Al2O3 and Al2O3/ZAO passivation layers. The a‐IGZO TFTs with Al2O3/ZAO stack exhibit high performance and excellent stabilities under electrical, thermal, and environmental tests with negligible threshold voltage shift. The origin of the device performances and improved stabilities are analyzed using X‐ray photoelectron spectroscopy and high‐resolution transmission electron microscopy analyses. It is found that the Zr elements diffuse into the a‐IGZO channel when ZAO is directly deposited on the a‐IGZO, resulting in the deterioration of the device performance. It is also found that the Al2O3 single layer on top of the a‐IGZO cannot protect the back‐channel from moisture diffusion. But a thin Al2O3 layer on top of the TFTs can protect the diffusion of Zr elements from ZAO into the a‐IGZO channel and enhances the performance and stabilities. Therefore, the low cost, Al2O3/ZAO stack by spray pyrolysis on the sputtered a‐IGZO can be an excellent passivation for highly stable metal‐oxide TFTs. [ABSTRACT FROM AUTHOR]

Ferroelectric transistors with a large memory window (MW) and operational stability have been of increasing interest recently. In this study, a ferroelectric thin‐film transistor (FE‐TFT) with a novel metal‐insulator‐semiconductor‐ferroelectric (MISF) structure is proposed. With the ferroelectric layer located under the semiconductor, the TFT process can be similar to a conventional coplanar structure with a SiO2 gate insulator (GI). In this work, both FE and active semiconductors are deposited by spray pyrolysis which is beneficial for large‐area and low‐cost manufacturing. The FE ZrO2 by spray pyrolysis has a nanocrystalline phase, and the semiconductor InGaO shows a polycrystalline structure. The TFT exhibits a MW of 5.6 V with an operating voltage range of −10–10 V. The device shows a low leakage current of 10−12 A, and thus the on/off ratio is >107 at VDS = 1.0 V. The device shows stable performance with increasing temperatures up to 80 °C. The endurance of the device is 5000 cycles at 0.1 Hz pulse with a negligible variation of MW less than 0.1 V, indicating excellent operational stability. [ABSTRACT FROM AUTHOR]

There is increasing interest in a ferroelectric transistor, mainly using vacuum processed hafnium oxide based materials. We report in this paper a solution processed ZnO thin-film transistor (TFT) with improved ferroelectric performance in Hf0.5Zr0.5O2 (HZO) using a triple layer of ZrOx/HZO/AlOx by spray pyrolysis. The performance enhancement is due to the difference in thermal expansion coefficient between the bottom/top dielectric and HZO layers. Grazing incident x-ray diffraction, current–voltage, capacitance–voltage, polarization–voltage, and anticlockwise hysteresis in transfer curve confirm the excellent ferroelectricity of the triple layer. A memory window as large as ∼3 V, the maximum on/off ratio of 3.5 × 109, the field-effect mobility of 125 cm2/V s, and the subthreshold slope of 0.18 V/decade were obtained from the ZnO TFT with the ZrOx/HZO/AlOx gate insulator, demonstrating the high performance ferroelectric ZnO TFT. This result can open opportunities for ferroelectric oxide TFT for large area electronics on glass, including display. [ABSTRACT FROM AUTHOR]

In 2 Se 3 , 2D ferroelectric-semiconductor, is a promising candidate for next-generation memory device because of its outstanding electrical properties. However, the large-area manufacturing of In 2 Se 3 is still a big challenge. In this work, spray pyrolysis technique is introduced for the growth of large-area In 2 Se 3 thin film. A polycrystalline γ-In 2 Se 3 layer can be grown on 15 cm × 15 cm glasss at the substrate temperature of 275 °C. The In 2 Se 3 ferroelectric-semiconductor field effect transistor (FeS-FET) on glass substrate demonstrates a large hysteresis window of 40.3 V at the ±40 V of gate voltage sweep and excellent uniformity. The FeS-FET exhibits an electron field effect mobility of 0.97 cm 2 V -1 s -1 and an on/off current ratio of >10 7 in the transfer curves. The memory behavior of the large-area, In 2 Se 3 FeS-FETs for next-generation memory is demonstrated., (© 2023 Wiley-VCH GmbH.)

Thin-film transistor (TFT) is a essential device for future electronics driving the next level of digital transformation. The development of metal-oxide-semiconductor (MOS) TFTs is considered one of the most advantageous devices for next-generation, large-area flexible electronics. This study demonstrates the systematic study of the amorphous gallium oxide (a-Ga 2 O 3 ) and its application to nanocrystalline ZnO TFTs. The TFT with a-Ga 2 O 3 /c-ZnO-stack channel exhibits a field-effect mobility of ∼41 cm 2 V -1 s -1 and excellent stability under positive-bias-temperature stress. The a-Ga 2 O 3 /c-ZnO-stack TFT on polyimide (PI) substrate exhibits a negligible threshold voltage shift upon 100k bending cycles with a radius of 3 mm and is very stable under environmental test. The smooth morphology with tiny grains of ∼12 nm diameter with fewer grain boundary states improves the charge transport in Ga 2 O 3 /ZnO-stack TFT. The existence of amorphous a-Ga 2 O 3 in between very thin ZnO layers helps to enhance the heterointerfaces and reduce the defect density in Ga 2 O 3 /ZnO interface. Therefore, integrating a-Ga 2 O 3 in the ZnO channel in stacked TFT can increase mobility and enhance stability for next-generation flexible TFT electronics.