Kyung Hee University · 工学
Professor Jewel Kumer Saha's research lab specializes in the development of high-performance, solution-processed oxide semiconductor thin-film transistors (TFTs) with a focus on spray pyrolysis deposition techniques. The lab explores novel materials and heterostructures—such as ZnO, AlZnO, YZnO, and doped ZnO—on various gate insulators (e.g., Al₂O₃, ZrOₓ) to enhance device mobility, stability, and scalability. Key research directions include defect engineering, surface passivation using rare-earth oxides (e.g., Y₂O₃, Gd₂O₃), and codoping strategies (e.g., Li/Gd) to simultaneously improve electrical performance and long-term reliability.
Figures are computed from collected data and may differ slightly.
Metal-oxide thin-film transistors (TFT) fabricated by spray pyrolysis are of increasing interest because of its simple process and scalability. A bottleneck issue is to get a bubble-free and dense material. We studied the effect of ammonium acetate (AA) addition in the oxide precursor solution on the performance of spray-coated ZnO TFTs. AA acts as a stabilizer, which increases the solubility of the solution and enhances the film quality by reducing the defects. With AA addition in ZnO precursor
Zinc sulphate (ZnSO4.7H2O), an inorganic material has been crystallized by an isothermal evaporation method. ZnSO4.7H2O is highly soluble in water and the solubility is found to be increased almost linearly with the increase of temperature. At room temperature around 34°C, the solubility was found to be 92.41 gm/50 ml. The FT-IR spectroscopy was performed on pure zinc sulphate crystals to identify the presence of functional groups. The grown crystals have been subjected to powder X-ray diffracti
We demonstrate a high mobility, triple-stack ZnO/AlZnO/YZnO heterojunction thin-film transistor (TFT) using the semiconductors deposited by spray pyrolysis at 350 °C on an Al<sub>2</sub>O<sub>3</sub> gate insulator. A thin layer (5 nm) of AlZnO on the top of ZnO used as an active layer of an inverted coplanar-structured TFT increases the field-effect mobility (μ<sub>FE</sub>) from 42.56 to 82.7 cm<sup>2</sup> V<sup>-1</sup> s<sup>-1</sup>. An additional 5 nm thick YZnO on the top of the ZnO/AlZn
We report a highly stable, nanocrystalline, zinc oxide (ZnO) thin-film transistor (TFT) fabricated by spray pyrolysis using purified ZrO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> as a gate insulator. The crystalline ZnO layer shows an average grain size of 30 nm and a smooth surface with an average rms roughness value of 1.21 nm. The smoothness of the ZnO film is due to the alignment of all grains with the (002) c-axis. The TFTs exhibi
We report the impact of yttrium oxide (YO<sub>x</sub>) passivation on the zinc oxide (ZnO) thin film transistor (TFT) based on Al<sub>2</sub>O<sub>3</sub> gate insulator (GI). The YO<sub>x</sub> and ZnO films are both deposited by spray pyrolysis at 400 and 350 °C, respectively. The YO<sub>x</sub> passivated ZnO TFT exhibits high device performance of field effect mobility (μ<sub>FE</sub>) of 35.36 cm<sup>2</sup>/Vs, threshold voltage (V<sub>TH</sub>) of 0.49 V and subthreshold swing (SS) of 128
Abstract The simultaneous doping effect of Gadolinium (Gd) and Lithium (Li) on zinc oxide (ZnO) thin‐film transistor (TFT) by spray pyrolysis using a ZrO x gate insulator is reported. Li doping in ZnO increases mobility significantly, whereas the presence of Gd improves the stability of the device. The Gd ratio in ZnO is varied from 0% to 20% and the Li ratio from 0% to 10%. The optimized ZnO TFT with codoping of 5% Li and 10% Gd exhibits the linear mobility of 25.87 cm 2 V −1 s −1 , the subthre
We report the fluorine (F) doping effect on zinc oxide (ZnO) thin-film transistor (TFT) fabricated by spray pyrolysis on spray-coated zirconia alumina oxide (ZAO) gate insulator. F doping was performed by NF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> plasma treatment on ZnO thin film. The ZnO film shows <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</i> -axis-aligned hexagonal structure, w
In this study, we present a comprehensive study on the fabrication and characterization of heterojunction In<sub>2</sub>O<sub>3</sub>/ZnO thin-film transistors (TFTs) aimed at exploiting the quantum confinement effect to enhance device performance. By systematically optimizing the thickness of the crystalline In<sub>2</sub>O<sub>3</sub> (c-In<sub>2</sub>O<sub>3</sub>) layer to create a narrow quantum well, we observed a significant increase in saturation mobility (μ<sub>SAT</sub>) from 12.76 to
This study presents the synthesis and characterization of MgZrO3, a high-dielectric-constant (k) material tailored for nanocrystalline indium gallium zinc oxide (IGZO) thin-film transistors (TFTs). MgZrO3 films were deposited via spray pyrolysis at 400 °C, yielding a uniform amorphous structure with enhanced surface quality, as confirmed by X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). A 30 nm MgZrO3 film e
We study the effect of mechanical bending on electrical characteristics of flexible ZnO TFTs by spray pyrolysis having μ SAT of 11.45 cm 2 /V.s on PI substrate at 350 °C. The flexible ZnO TFTs exhibit robust electrical characteristics (|ΔV TH |=0.6V) under mechanical‐strain up to 1% and even after repetitive bending for 10 4 cycles (|ΔV TH |=0.33V).
We demonstrate the low‐cost AlZnO/ZnO TFT by spray pyrolysis at 350 °C. High field‐effect mobility is achieved over 80 cm 2 /V.s with a subthreshold slope of 123 mV/decade. The higher mobility is due to the 2D like electron gas at the interface of AlZnO/ZnO. The stack TFT shows positive threshold voltage and negligible threshold voltage shift under positive bias stress. The presence of Al‐O at the interface reduces the oxygen vacancies and improves the bias stability.
We report spray-pyrolyzed ZnO thin-film transistors (TFTs) doped with alkali metals (Li, Na, K, Rb, and Cs) to tune the threshold voltage (VTH) while preserving lattice strain. The varying atomic radii of alkali dopants modulate strain in the ZnO lattice, significantly impacting its electronic and structural properties. The optical band gap ranges from 3.16 to 3.25 eV, with shallow donor states enhancing near-band-edge (NBE) and UV emission around 400 nm. While the band gap remains nearly consta
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