Introduction on atomic layer deposition for high-k dielectric & high mobility oxide semiconductor thin film transistors

Amorphous oxide semiconductors have been widely studied for the potential use in flat panel displays such as active matrix liquid crystal display (LCD) and Organic light emitting diodes (OLEDs). Since reporting amorphous InGaZnO semiconductor thin film transistor (TFT) in 2003 & 2004, many multi-component oxide semiconductors have been intensively investigated and developed by reactive sputtering method. Very recently, the sputtered InGaZnO TFTs are already adopted in mass-production to fabricate AMOLED TVs. However, there remain several problems such as high mobility & stability issues. Also, virtual and argument reality (VR, AR) applications are rapidly emerging in display markets but the main issues are high resolution and low-voltage driving technologies. Please click Additional Files below to see the full abstract

Whole-genome sequencing and comparative genomics analysis of a newly emerged multidrug-resistant Klebsiella pneumoniae isolate of ST967

Whole-genome sequencing and population genetics analysis of K. pneumoniae are scarce from LMICs, and none has been reported for Armenia. Multilevel comparative analysis revealed that ARM01 (an isolate belonging to a newly emerged K. pneumoniae ST967 lineage) was genetically similar to two isolates recovered from Qatar

STUDY ON THE EFFECT OF RESIDUAL STRESS FIELD ON THE CRACK GROWTH RATE OF CIVIL WELDED PLATE

In order to reduce the cost of fatigue crack growth test and shorten the research period of welding process on new aircraft siding structure,this paper uses Abaqus finite element software to simulate welding residual stress field by using predefined temperature field method.The stress intensity factor values of crack tip are obtained by finite element simulation.Based on the structural characteristics of large welded plate,the Pairs formula was used to predict the crack propagation rate of welded plate.Based on this model,the fatigue crack growth rate of specimens with different stress ratio and welding process was studied.It is found that the effective stress ratio increases with the residual stress,but the effect decreases with the increase of the stress ratio.The trend of the effective stress ratio is similar to that of the residual stress distribution.The welding residual stress increases the crack growth rate of the welded structure.The feasibility of the proposed method is verified by comparison with the experimental results

STUDY ON ESTIMATION METHOD OF TENSILE STRENGTH OF AIRCRAFT STIFFENED-WELED PLATE

This paper studied methods to predict the tensile strength of stiffened-welded plate structure for civil aircraft welding. Based on the law of elastic modulus in the composite material mechanics,a theoretical formula is proposed to estimate the tensile strength of the aircraft welding plate structure,and through the introduction of the mechanical properties of the welded joints,out of plane moment,long truss shape,skin stress concentration four the coefficient,reflecting the influence of factors on the strength of the welded plate structure. The results show that the theoretical calculation is 3. 81% larger than the experimental value,and the error is small,which proves that the theoretical formula established by this study has certain reliability and correctness. The estimation method can provide a reference for the selection of stiffened-welded plate structure material,the improvement of process performance and the aerospace designers ’ estimated strength value of aircraft stiffened-welded plate structure. In addition,the tensile mechanical behaviors of two groups of welding plate with different welding states were simulated and analyzed by using the finite element method. The results show that the cracking state of the weld has no great influence on the tensile strength of the stiffened-welded plate,and through the finite element stress cloud can be observed in the welding plate of the high stress area,showing the failure process,in the future for the new civil welding wall structure design and selection of preresearch stage. The finite element simulation is used to replace the tensile test of large structural members of aircraft siding,reduce the cycle and cost of pre-research,and improve the efficiency of the test

Atomic Layer Deposition of an Indium Gallium Oxide Thin Film for Thin-Film Transistor Applications

Indium gallium oxide (IGO) thin films were deposited via atomic layer deposition (ALD) using [1,1,1-trimethyl-<i>N</i>-(trimethylsilyl)­silanaminato]­indium (InCA-1) and trimethylgallium (TMGa) as indium and gallium precursors, respectively, and hydrogen peroxide as the reactant. To clearly understand the mechanism of multicomponent ALD growth of oxide semiconductor materials, several variations in the precursor–reactant deposition cycles were evaluated. Gallium could be doped into the oxide film at 200 °C when accompanied by an InCA-1 pulse, and no growth of gallium oxide was observed without the simultaneous deposition of indium oxide. Density functional theory calculations for the initial adsorption of the precursors revealed that chemisorption of TMGa was kinetically hindered on hydroxylated SiO<i>_x</i> but was spontaneous on a hydroxylated InO<i>_x</i> surface. Moreover, the atomic composition and electrical characteristics, such as carrier concentration and resistivity, of the ALD-IGO film were controllable by adjusting the deposition supercycles, composed of InO and GaO subcycles. Thus, ALD-IGO could be employed to fabricate active layers for thin-film transistors to realize an optimum mobility of 9.45 cm²/(V s), a threshold voltage of −1.57 V, and a subthreshold slope of 0.26 V/decade

Flexible and High-Performance Amorphous Indium Zinc Oxide Thin-Film Transistor Using Low-Temperature Atomic Layer Deposition

Amorphous indium zinc oxide (IZO) thin films were deposited at different temperatures, by atomic layer deposition (ALD) using [1,1,1-trimethyl-<i>N</i>-(trimethylsilyl)­silanaminato]indium (INCA-1) as the indium precursor, diethlzinc (DEZ) as the zinc precursor, and hydrogen peroxide (H₂O₂) as the reactant. The ALD process of IZO deposition was carried by repeated supercycles, including one cycle of indium oxide (In₂O₃) and one cycle of zinc oxide (ZnO). The IZO growth rate deviates from the sum of the respective In₂O₃ and ZnO growth rates at ALD growth temperatures of 150, 175, and 200 °C. We propose growth temperature-dependent surface reactions during the In₂O₃ cycle that correspond with the growth-rate results. Thin-film transistors (TFTs) were fabricated with the ALD-grown IZO thin films as the active layer. The amorphous IZO TFTs exhibited high mobility of 42.1 cm² V^–1 s^–1 and good positive bias temperature stress stability. Finally, flexible IZO TFT was successfully fabricated on a polyimide substrate without performance degradation, showing the great potential of ALD-grown TFTs for flexible display applications

Amorphous IGZO TFT with High Mobility of similar to 70 cm(2)/(V s) via Vertical Dimension Control Using PEALD

Amorphous InGaZnOx (a-IGZO) thin-film transistors (TFTs) are currently used in flat-panel displays due to their beneficial properties. However, the mobility of similar to 10 cm(2)/(V s) for the a-IGZO TFTs used in commercial organic light-emitting diode TVs is not satisfactory for high-resolution display applications such as virtual and augmented reality applications. In general, the electrical properties of amorphous oxide semiconductors are strongly dependent on their chemical composition; the indium (In)-rich IGZO achieves a high mobility of 50 cm(2)/(V s). However, the In-rich IGZO TFTs possess another issue of negative threshold voltage owing to intrinsically high carrier density. Therefore, the development of an effective way of carrier density suppression in In-rich IGZO will be a key strategy to the realization of practical high-mobility a-IGZO TFTs. In this study, we report that In-rich IGZO TFTs with vertically stacked InOx, ZnOx, and GaOx atomic layers exhibit excellent performances such as saturation mobilities of similar to 74 cm(2)/(V s), threshold voltage of -1.3 V, on/off ratio of 8.9 X 10(8), subthreshold swing of 0.26 V/decade, and hysteresis of 0.2 V, while keeping a reasonable carrier density of similar to 10(17) cm(-3). We found that the vertical dimension control of IGZO active layers is critical to TFT performance parameters such as mobility and threshold voltage. This study illustrates the potential advantages of atomic layer deposition processes for fabricating ultrahigh-mobility oxide TFTs

A Study on the Electrical Properties of Atomic Layer Deposition Grown InO_<i>x</i> on Flexible Substrates with Respect to N₂O Plasma Treatment and the Associated Thin-Film Transistor Behavior under Repetitive Mechanical Stress

Indium oxide (InO_<i>x</i>) films were deposited at low processing temperature (150 °C) by atomic layer deposition (ALD) using [1,1,1-trimethyl-<i>N</i>-(trimethylsilyl)­silanaminato]­indium (InCA-1) as the metal precursor and hydrogen peroxide (H₂O₂) as the oxidant. As-deposited InO_<i>x</i> exhibits a metallic conductor-like behavior owing to a relatively high free-carrier concentration. In order to control the electron density in InO_<i>x</i> layers, N₂O plasma treatment was carried out on the film surface. The exposure time to N₂O plasma was varied (600–2400 s) to evaluate its effect on the electrical properties of InO_<i>x</i>. In this regard, thin-film transistors (TFTs) utilizing this material as the active layer were fabricated on polyimide substrates, and transfer curves were measured. As the plasma treatment time increases, the TFTs exhibit a transition from metal-like conductor to a high-performance switching device. This clearly demonstrates that the N₂O plasma has an effect of diminishing the carrier concentration in InO_<i>x</i>. The combination of low-temperature ALD and N₂O plasma process offers the possibility to achieve high-performance devices on polymer substrates. The electrical properties of InO_<i>x</i> TFTs were further examined with respect to various radii of curvature and repetitive bending of the substrate. Not only does prolonged cyclic mechanical stress affect the device properties, but the bending direction is also found to be influential. Understanding such behavior of flexible InO_<i>x</i> TFTs is anticipated to provide effective ways to design and achieve reliable electronic applications with various form factors

Growth and DNA Methylation Alteration in Rice (<i>Oryza sativa</i> L.) in Response to Ozone Stress

With the development of urban industrialization, the increasing ozone concentration (O3) at ground level stresses on the survival of plants. Plants have to adapt to ozone stress. DNA methylation is crucial for a rapid response to abiotic stress in plants. Little information is known regarding the epigenetic response of DNA methylation of plants to O3 stress. This study is designed to explore the epigenetic mechanism and identify a possible core modification of DNA methylation or genes in the plant, in response to O3 stress. We investigated the agronomic traits and genome-wide DNA methylation variations of the Japonica rice cultivar Nipponbare in response to O3 stress at three high concentrations (80, 160, and 200 nmol·mol−1), simulated using open-top chambers (OTC). The flag leaf length, panicle length, and hundred-grain weight of rice showed beneficial effects at 80 nmol·mol−1 O3 and an inhibitory effect at both 160 and 200 nmol·mol−1 O3. The methylation-sensitive amplified polymorphism results showed that the O3-induced genome-wide methylation alterations account for 14.72–15.18% at three different concentrations. Our results demonstrated that methylation and demethylation alteration sites were activated throughout the O3 stress, mainly at CNG sites. By recovering and sequencing bands with methylation alteration, ten stress-related differentially amplified sequences, widely present on different chromosomes, were obtained. Our findings show that DNA methylation may be an active and rapid epigenetic response to ozone stress. These results can provide us with a theoretical basis and a reference to look for more hereditary information about the molecular mechanism of plant resistance to O3 pollution