Observation of B+ → χc0K+

journal articl

海水の作用を受けるセメントペーストマトリックスの凍結挙動がスケーリングに及ぼす影響について

journal articl

Dual Role of AgNO3 as an Oxidizer and Chloride Remover toward Enhanced Combustion Synthesis of Low-Voltage and Low-Temperature Amorphous Rare Metal-Free Oxide Thin-Film Transistors

SnO2 transistors show great promise as an alternative to existing In2O3-based transistors, considering their abundance and similar electronic properties. However, they suffer from highly negative on-voltages, large subthreshold swings, and high processing temperatures. One of the reasons for this is the residual chloride in the SnO2 film, which negatively impacts the transistor by increasing the defects or acting as a dopant, thereby shifting the turn-on voltage negatively and increasing the subthreshold swing. Herein, we present a facile method of producing SixSnyO films with fewer chloride impurities, which can be used in high-performance, solution-processed TFTs. We employed AgNO3 as an oxidizer for a low-temperature combustion reaction at 300 °C, which simultaneously acts as a chloride remover. We successfully reduced the turn-on voltage from −35.0 to −0.7 V using this route. The subthreshold swing was decreased from 2.91 to 0.32 V/dec using the same Sn concentration. The highest mobility obtained was 1.92 cm2/(V s) from the 0.25 M Sn precursor at a low drain voltage of 0.1 V. This method can be used as a general route for fabricating solution process-based SnO2 TFTs and further expanding its application to flexible devices via low-temperature combustion.journal articl

Effect of Average Grain Size on the Uniformity and Ferroelectricity of BTO/PSX Thin Films Processed by Low-Temperature Solution Method

In this study, we utilized 50 nm BaTiO3 (BTO) nanoparticles and polysiloxane (PSX) with a higher concentration of methyl and silica groups to fabricate insulating layers at a low curing temperature of 100 °C using a solution-based method. This approach aims to enhance film uniformity while retaining the ferroelectric properties. Consequently, we maintained a minimal leakage current in thin-film transistors (TFTs) while achieving transfer characteristics characterized by a distinct hysteresis. Moreover, we verified the presence of ferroelectricity in 50 nm BTO nanoparticles. Compared with prior research, we confirm that decreasing nanoparticle size effectively reduces film roughness but also leads to a reduction in polarization intensity due to smaller diameter BTO nanoparticles. Additionally, a higher proportion of methyl and silica groups effectively lowers the curing temperature of PSX. At the same time, the hydrogen ions released in the polycondensation reaction can also effectively suppress the oxygen vacancies at the interface between dielectric and channel layers, improving the TFT electrical characteristics.journal articl

Performance and Stability Enhancement of Fully Solution-Processed a-InZnO Thin-Film Transistors via Argon Plasma Treatment

The market is now moving to next-generation flexible electronics which requires the integration of functional solution-processed materials using simple and low-temperature fabrication techniques that are compatible with heat-sensitive substrates. Although several studies have reported on the high-performance solution-processed layer in oxide thin-film transistors (TFTs), achieving high mobility while maintaining good stability under the bias stress test remains a challenge. In this report, we show that argon (Ar) plasma treatment is an effective method for achieving fully solution-processed amorphous indium zinc oxide (a-IZO) TFTs with high stability and performance. Particularly, Ar plasma treatment can activate the electrode and induce TFT switching. The electrical performance of the a-IZO TFT was also enhanced by the Ar plasma treatment. From the experimental results, fully solution-processed a-IZO TFTs with high mobility up to 31.12 cm2/(V s) was achieved by Ar plasma treatment for 5 s at an Ar flow rate of 75 sccm. The stability behavior of the self-aligned top gate top contact a-IZO TFT treated with argon plasma was investigated under positive bias stress (PBS) and negative bias stress (NBS) with a smallest threshold voltage shift (ΔVth) of −0.3 and 0.7 V for PBS and NBS, respectively. ΔVth is improved due to the higher film densification which confirms better film quality. Higher mobile carrier with lower interface trap density and film densification are the main reasons behind the performance and stability improvement of these TFTs. These results show that the performance and stability enhancement of the fully solution-processed a-IZO TFT by plasma treatment has a large potential for future low-temperature flexible device applications.journal articl

High gain complementary inverters based on comparably-sized IGZO and DNTT source-gated transistors

We report the first implementation of a complementary circuit using thin-film source-gated transistors (SGTs). The n-channel and p-channel SGTs were fabricated using the inorganic and organic semiconductors amorphous InGaZnO (IGZO) and dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene (DNTT), respectively. The SGTs exhibit flat output characteristics and early saturation (dVDSAT/dVGS = 0.2 and 0.3, respectively), even in the absence of lateral field-relief structures, thanks to the rectifying source contacts realized with Pt and Ni, respectively. Hence, the complementary inverter shows excellent small-signal gain of 368 V V−1 and noise margin exceeding 94% of the theoretical maximum. We show that the trip point of such inverters can be tuned optically, with interesting applications in compact detectors and sensors. Numerical simulation, using Silvaco ATLAS, reveals that optimized and monolithically-integrated SGT-based complementary inverters may reach a small-signal gain over 9000 V V−1, making them highly suited to low and moderate speed digital thin-film applications. This proof-of-concept demonstration provides encouraging results for further integration and circuit level optimizations.journal articl

High-k Solution-Processed Barium Titanate/Polysiloxane Nanocomposite for Low-Temperature Ferroelectric Thin-Film Transistors

Ferroelectric nanoparticles have attracted much attention for numerous electronic applications owing to their nanoscale structure and size-dependent behavior. Barium titanate (BTO) nanoparticles with two different sizes (20 and 100 nm) were synthesized and mixed with a polysiloxane (PSX) polymer forming a nanocomposite solution for high-k nanodielectric films. Transition from the ferroelectric to paraelectric phase of BTO with different nanoparticle dimensions was evaluated through variable-temperature X-ray diffraction measurement accompanied by electrical analysis using capacitor structures. A symmetric single 200 peak was constantly detected at different measurement temperatures for the 20 nm BTO sample, marking a stable cubic crystal structure. 100 nm BTO on the other hand shows splitting of 200/002 peaks correlating to a tetragonal crystal form which further merged, thus forming a single 200 peak at higher temperatures. Smaller BTO dimension exhibits clockwise hysteresis in capacitance–voltage measurement and correlates to a cubic crystal structure which possesses paraelectric properties. Bigger BTO dimension in contrast, demonstrates counterclockwise hysteresis owing to their tetragonal crystal form. Through further Rietveld refinement analysis, we found that the tetragonality (c/a) of 100 nm BTO decreases at a higher temperature which narrows the hysteresis window. A wider hysteresis window was observed when utilizing 100 nm BTO compared to 20 nm BTO even at a lower loading ratio. The present findings imply different hysteresis mechanisms for BTO nanoparticles with varying dimensions which is crucial in understanding the role of how the BTO size tunes the crystal structures for integration in thin-film transistor devices.journal articl