Influence of Post-UV/Ozone Treatment of Ultrasonic-Sprayed Zirconium Oxide Dielectric Films for a Low-Temperature Oxide Thin Film Transistor

Solution-processed zirconium acetylacetonate charge-trap layer for multi-bit nonvolatile thin-film memory transistors

The charge trap property of solution-processed zirconium acetylacetonate (ZAA) for solution-processed nonvolatile charge-trap memory (CTM) transistors is demonstrated. Increasing the annealing temperature of the ZAA from room temperature (RT) to 300°C in ambient, the carbon double bonds within the ZAA decreases. The RT-dried ZAA for the p-type organic-based CTM shows the widest threshold voltage shift (∆VTH ≈ 80 V), four distinct VTHs for a multi-bit memory operation and retained memory currents for 103 s with high memory on- and off-current ratio (IM,ON/IM,OFF ≈ 5Ⅹ104). The n-type oxide-based CTM (Ox-CTM) also shows a ∆VTH of 14 V and retained memory currents for 103 s with IM,ON/IM,OFF ≈ 104. The inability of the Ox-CTM to be electrically erasable is well explained with simulated electrical potential contour maps. It is deduced that, irrespective of the varied solution-processed semiconductor used, the RT-dried organic ZAA as CTL shows the best memory functionality in the fabricated CTMs. This implies that the high carbon double bonds in the low-temperature processed ZAA CTL are very useful for low-cost multi-bit CTMs in flexible electronics.

Fatigue-Induced Surface Modification of Zr-Based Metallic Glass under Environmental Conditions

Metallic glass (MG), an intrinsic heterogeneous structure at the atomic scale, is one of the promising engineering materials with intriguing physical properties. MG often suffers from the fatigue issue caused by the repetitive mechanical loading, but it is still elusive how the local heterogeneity evolves and affects the macroscale fatigue and deformation against bulky external stress. In this study, we investigate the fatigue effect in Zr-Cu-Al ribbon using a bending fatigue method. We used scanning probe microscopy (SPM) in parallel with X-ray diffraction and X-ray photoelectron spectroscopy to figure out the loading effect on the local heterogeneities. The spatially resolved SPM images show that there is a local fluctuation of mechanical and electrical properties on the fatigued side along with morphological deformation compared to the unloaded side. Approaching the broken edge where the fatigue failure occurs, the decaying tendency is not only more dominant but also accelerated by surface oxidation of the fatigued regions. Our study provides a useful guideline on how to monitor structural changes of MGs under fatigue conditions in service and will open a door toward commercialization of high-performance structural engineering materials.

Reduction of Hysteresis in Hybrid Perovskite Transistors by Solvent-Controlled Growth

The effect of crystallization process speed on the morphology of solution-processed methyl ammonium lead iodide (MAPbI₃) thin films is investigated. Crystallization speed is controlled by varying the number of annealing steps, temperature, and resting time between steps. The resting period allows solvent-controlled growth (SCG) in which crystallization progresses slowly via an intermediate phase—during which solvents slowly evaporate away from the films. SCG results in fewer residues, fewer pinholes, and larger grain sizes. Consequently, thin-film transistors with SCG MAPbI₃ exhibit smaller hysteresis in their current-voltage characteristics than those without, demonstrating the benefits of SCG toward hysteresis-free perovskite devices.

Research Progress of High Dielectric Constant Zirconia-Based Materials for Gate Dielectric Application

The high dielectric constant ZrO2, as one of the most promising gate dielectric materials for next generation semiconductor device, is expected to be introduced as a new high k dielectric layer to replace the traditional SiO2 gate dielectric. The electrical properties of ZrO2 films prepared by various deposition methods and the main methods to improve their electrical properties are introduced, including doping of nonmetal elements, metal doping design of pseudo-binary alloy system, new stacking structure, coupling with organic materials and utilization of crystalline ZrO2 as well as optimization of low-temperature solution process. The applications of ZrO2 and its composite thin film materials in metal oxide semiconductor field effect transistor (MOSFET) and thin film transistors (TFTs) with low power consumption and high performance are prospected.

Tuneable Functionalization of Glass Fibre Membranes with ZnO/SnO2 Heterostructures for Photocatalytic Water Treatment: Effect of SnO2 Coverage Rate on the Photocatalytic Degradation of Organics

The construction of a ZnO/SnO2 heterostructure is considered in the literature as an efficient strategy to improve photocatalytic properties of ZnO due to an electron/hole delocalisation process. This study is dedicated to an investigation of the photocatalytic performance of ZnO/SnO2 heterostructures directly synthesized in macroporous glass fibres membranes. Hydrothermal ZnO nanorods have been functionalized with SnO2 using an atomic layer deposition (ALD) process. The coverage rate of SnO2 on ZnO nanorods was precisely tailored by controlling the number of ALD cycles. We highlight here the tight control of the photocatalytic properties of the ZnO/SnO2 structure according to the coverage rate of SnO2 on the ZnO nanorods. We show that the highest degradation of methylene blue is obtained when a 40% coverage rate of SnO2 is reached. Interestingly, we also demonstrate that a higher coverage rate leads to a full passivation of the photocatalyst. In addition, we highlight that 40% coverage rate of SnO2 onto ZnO is sufficient for getting a protective layer, leading to a more stable photocatalyst in reuse.