Correction: Chen et al. New n-p Junction Floating Gate to Enhance the Operation Performance of a Semiconductor Memory Device. Materials 2022, 15, 3640.

The authors would like to make corrections to a recently published paper [...].

New n-p Junction Floating Gate to Enhance the Operation Performance of a Semiconductor Memory Device.

To lower the charge leakage of a floating gate device and improve the operation performance of memory devices toward a smaller structure size and a higher component capability, two new types of floating gates composed of pn-type polysilicon or np-type polysilicon were developed in this study. Their microstructure and elemental compositions were investigated, and the sheet resistance, threshold voltages and erasing voltages were measured. The experimental results and charge simulation indicated that, by forming an n-p junction in the floating gate, the sheet resistance was increased, and the charge leakage was reduced because of the formation of a carrier depletion zone at the junction interface serving as an intrinsic potential barrier. Additionally, the threshold voltage and erasing voltage of the np-type floating gate were elevated, suggesting that the performance of the floating gate in the operation of memory devices can be effectively improved without the application of new materials or changes to the physical structure.

Tunable multilevel storage of complementary resistive switching on single-step formation of ZnO/ZnWO(x) bilayer structure via interfacial engineering.

Tunable multilevel storage of complementary resistive switching (CRS) on single-step formation of ZnO/ZnWOx bilayer structure via interfacial engineering was demonstrated for the first time. In addition, the performance of the ZnO/ZnWOx-based CRS device with the voltage- and current-sweep modes was demonstrated and investigated in detail. The resistance switching behaviors of the ZnO/ZnWOx bilayer ReRAM with adjustable RESET-stop voltages was explained using an electrochemical redox reaction model whose electron-hopping activation energies of 28, 40, and 133 meV can be obtained from Arrhenius equation at RESET-stop voltages of 1.0, 1.3, and 1.5 V, respectively. In the case of the voltage-sweep operation on the ZnO-based CRS device, the maximum array numbers (N) of 9, 15, and 31 at RESET-stop voltages of 1.4, 1.5, and 1.6 V were estimated, while the maximum array numbers increase into 47, 63, and 105 at RESET-stop voltages of 2.0, 2.2, and 2.4 V, operated by the current-sweep mode, respectively. In addition, the endurance tests show a very stable multilevel operation at each RESET-stop voltage under the current-sweep mode.

Effect of titanium addition on the thermal properties of diamond/cu-ti composites fabricated by pressureless liquid-phase sintering technique.

In this study, minor-addition elements such as Si, Co, Cr, W, Mo, and Ti were added to matrix to improve the wettability between the diamonds and Cu matrix. The pressureless liquid-phase sintering technique adopted in this study provides a low-cost method for producing diamond/Cu composites with high potential for industrial mass production. Thermal properties of the diamond/Cu-Ti composites fabricated by pressureless liquid-phase sintering at 1373 K with variation in Ti contents were thoroughly investigated. XRD and TEM analysis show that TiC layer formed in the interface between Cu and diamond. The composites exhibited thermal conductivity as high as 620 W/m · K for 50 vol% diamond/Cu-0.6 at % Ti composite with diamond particle size of 300 µm. This value comes up to 85% of the thermal conductivity calculated by the Hasselman and Johnson (H-J) theoretical analysis. Under these conditions, a suitable coefficient of thermal expansion of 6.9 ppm/K was obtained.

Structural and thermodynamic factors of suppressed interdiffusion kinetics in multi-component high-entropy materials.

We report multi-component high-entropy materials as extraordinarily robust diffusion barriers and clarify the highly suppressed interdiffusion kinetics in the multi-component materials from structural and thermodynamic perspectives. The failures of six alloy barriers with different numbers of elements, from unitary Ti to senary TiTaCrZrAlRu, against the interdiffusion of Cu and Si were characterized, and experimental results indicated that, with more elements incorporated, the failure temperature of the barriers increased from 550 to 900°C. The activation energy of Cu diffusion through the alloy barriers was determined to increase from 110 to 163 kJ/mole. Mechanistic analyses suggest that, structurally, severe lattice distortion strains and a high packing density caused by different atom sizes, and, thermodynamically, a strengthened cohesion provide a total increase of 55 kJ/mole in the activation energy of substitutional Cu diffusion, and are believed to be the dominant factors of suppressed interdiffusion kinetics through the multi-component barrier materials.

Stability scheme of ZnO-thin film resistive switching memory: influence of defects by controllable oxygen pressure ratio.

We report a stability scheme of resistive switching devices based on ZnO films deposited by radio frequency (RF) sputtering process at different oxygen pressure ratios. I-V measurements and statistical results indicate that the operating stability of ZnO resistive random access memory (ReRAM) devices is highly dependent on oxygen conditions. Data indicates that the ZnO film ReRAM device fabricated at 10% O2 pressure ratio exhibits the best performance. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) of ZnO at different O2 pressure ratios were investigated to reflect influence of structure to the stable switching behaviors. In addition, PL and XPS results were measured to investigate the different charge states triggered in ZnO by oxygen vacancies, which affect the stability of the switching behavior.

High sensitivity of middle-wavelength infrared photodetectors based on an individual InSb nanowire.

Single-crystal indium antimony (InSb) nanowire was fabricated into middle-infrared photodetectors based on a metal-semiconductor-metal (M-S-M) structure. The InSb nanowires were synthesized using an electrochemical method at room temperature. The characteristics of the FET reveal an electron concentration of 3.6 × 1017 cm-3 and an electron mobility of 215.25 cm2 V-1 s-1. The photodetectors exhibit good photoconductive performance, excellent stability, reproducibility, superior responsivity (8.4 × 104 A W-1), and quantum efficiency (1.96 × 106%). These superior properties are attributed to the high surface-to-volume ratio and single-crystal 1D nanostructure of photodetectors that significantly reduce the scattering, trapping, and the transit time between the electrodes during the transport process. Furthermore, the M-S-M structure can effectively enhance space charge effect by the formation of the Schottky contacts, which significantly assists with the electron injection and photocurrent gain.

Single-step formation of ZnO/ZnWO(x) bilayer structure via interfacial engineering for high performance and low energy consumption resistive memory with controllable high resistance states.

A spontaneously formed ZnO/ZnWOx bilayer resistive memory via an interfacial engineering by one-step sputtering process with controllable high resistance states was demonstrated. The detailed formation mechanism and microstructure of the ZnWOx layer was explored by X-ray photoemission spectroscopy (XPS) and transmission electron microscope in detail. The reduced trapping depths from 0.46 to 0.29 eV were found after formation of ZnWOx layer, resulting in an asymmetric I-V behavior. In particular, the reduction of compliance current significantly reduces the switching current to reach the stable operation of device, enabling less energy consumption. Furthermore, we demonstrated an excellent performance of the complementary resistive switching (CRS) based on the ZnO/ZnWOx bilayer structure with DC endurance >200 cycles for a possible application in three-dimensional multilayer stacking.

Dynamic evolution of conducting nanofilament in resistive switching memories.

Resistive random access memory (ReRAM) has been considered the most promising next-generation nonvolatile memory. In recent years, the switching behavior has been widely reported, and understanding the switching mechanism can improve the stability and scalability of devices. We designed an innovative sample structure for in situ transmission electron microscopy (TEM) to observe the formation of conductive filaments in the Pt/ZnO/Pt structure in real time. The corresponding current-voltage measurements help us to understand the switching mechanism of ZnO film. In addition, high-resolution transmission electron microscopy (HRTEM) and electron energy loss spectroscopy (EELS) have been used to identify the atomic structure and components of the filament/disrupted region, determining that the conducting paths are caused by the conglomeration of zinc atoms. The behavior of resistive switching is due to the migration of oxygen ions, leading to transformation between Zn-dominated ZnO(1-x) and ZnO.

Manipulated transformation of filamentary and homogeneous resistive switching on ZnO thin film memristor with controllable multistate.

A bias polarity-manipulated transformation from filamentary to homogeneous resistive switching was demonstrated on a Pt/ZnO thin film/Pt device. Two types of switching behaviors, exhibiting different resistive switching characteristics and memory performances were investigated in detail. The detailed transformation mechanisms are systematically proposed. By controlling different compliance currents and RESET-stop voltages, controllable multistate resistances in low resistance states and a high resistance states in the ZnO thin film metal-insulator-metal structure under the homogeneous resistive switching were demonstrated. We believe that findings would open up opportunities to explore the resistive switching mechanisms and performance memristor with multistate storage.

Room temperature-synthesized vertically aligned InSb nanowires: electrical transport and field emission characteristics.

Vertically aligned single-crystal InSb nanowires were synthesized via the electrochemical method at room temperature. The characteristics of Fourier transform infrared spectrum revealed that in the syntheses of InSb nanowires, energy bandgap shifts towards the short wavelength with the occurrence of an electron accumulation layer. The current-voltage curve, based on the metal-semiconductor-metal model, showed a high electron carrier concentration of 2.0 × 1017 cm-3 and a high electron mobility of 446.42 cm2 V-1 s-1. Additionally, the high carrier concentration of the InSb semiconductor with the surface accumulation layer induced a downward band bending effect that reduces the electron tunneling barrier. Consequently, the InSb nanowires exhibit significant field emission properties with an extremely low turn-on field of 1.84 V µm-1 and an estimative threshold field of 3.36 V µm-1.

Sn-doped In2O3 nanowires: enhancement of electrical field emission by a selective area growth.

Selective area growth of single crystalline Sn-doped In2O3 (ITO) nanowires synthesized via vapor-liquid-solid (VLS) method at 600°C was applied to improve the field emission behavior owing to the reduction of screen effect. The enhanced field emission performance reveals the reduction of turn-on fields from 9.3 to 6.6 V µm-1 with increase of field enhancement factors (ß) from 1,621 to 1,857 after the selective area growth at 3 h. Moreover, we find that the screen effect also highly depends on the length of nanowires on the field emission performance. Consequently, the turn-on fields increase from 6.6 to 13.6 V µm-1 with decreasing ß values from 1,857 to 699 after the 10-h growth. The detailed screen effect in terms of electrical potential and NW density are investigated in details. The findings provide an effective way of improving the field emission properties for nanodevice application.

Synthesis of single crystal Sn-doped In2O3 nanowires: size-dependent conductive characteristics.

Single crystalline Sn doped In(2)O(3) (ITO) NWs (nanowires) were synthesized via an Au-catalyzed VLS (vapor-liquid-solid) method at 600 °C. The different sizes (~20, ~40, ~80 nm) of the Au NPs (nanoparticles) provided the controllable diameters for ITO NWs during growth. Phase and microstructures confirmed by high-resolution transmission electron microscope images (HRTEM) and X-ray diffraction (XRD) spectra indicated that the phase of In(2)O(3) NWs had a growth direction of [100]. X-ray photoelectron spectroscopy (XPS) was employed to obtain the chemical compositions of the ITO NWs as well as the ratio of Sn/In and oxygen concentrations. The findings indicated that low resistivity was found for ITO NWs with smaller diameters due to higher concentrations of oxygen vacancies and less incorporation of Sn atoms inside the NWs. The resistivity of NWs increases with increasing diameter due to more Sn atoms being incorporated into the NW and their reduction of the amount of oxygen vacancies. Low resistivity NWs could be achieved again due to excess Sn atoms doped into the large diameter NWs. Therefore, by optimizing the well-controlled growth of the NW diameter and interface states, we are able to tune the electrical properties of Sn-doped ITO NWs.

Epitaxial photostriction-magnetostriction coupled self-assembled nanostructures.

Self-assembled vertical nanostructures take advantage of high interface-to-volume ratio and can be used to design new functionalities by the choice of a proper combination of constituents. However, most of the studies to date have emphasized the functional controllability of the nanostructures using external electric or magnetic fields. In this study, to introduce light (or photons) as an external control parameter in a self-assembled nanostructure system, we have successfully synthesized oxide nanostructures with CoFe(2)O(4) nanopillars embedded in a SrRuO(3) matrix. The combination of photostrictive SrRuO(3) and magnetostrictive CoFe(2)O(4) in the intimately assembled nanostructures leads to a light-induced, ultrafast change in magnetization of the CoFe(2)O(4) nanopillars. Our work demonstrates a novel concept on oxide nanostructure design and opens an alternative pathway for the explorations of diverse functionalities in heteroepitaxial self-assembled oxide nanostructures.

Misorientation control and functionality design of nanopillars in self-assembled perovskite-spinel heteroepitaxial nanostructures.

In this study, advanced control of crystallographic orientations and magnetic properties of self-assembled nanostructures via rational selections of substrates is demonstrated. We show that in the perovskite-spinel BiFeO(3)-CoFe(2)O(4) model system the crystal orientation of self-assembled CoFe(2)O(4) nanopillars can be tuned among (001), (011), and (111), while that of the BiFeO(3) matrix is fixed in (001). Moreover, the resultant CoFe(2)O(4) nanopillars appear in various shapes: pyramid, roof, and triangular platform, respectively. The tunable nanostructures through this approach enable the control of material functionality such as the magnetic anisotropy of CoFe(2)O(4). This study opens a new pathway for the engineering of self-assembled heteroepitaxial nanostructures.

The zone-refine driven growth of jellyfish-like core-shell nanowires.

Thermal evaporation of a Sn-silica mixture produces core-shell nanowires assembled into jellyfish-like structures. The growth mechanism involves zone-refine driven phase separation at the solid-liquid interface. The materials emit blue and red lights; the luminescence centers are discussed and verified.

In situ real-time investigation of cancer cell photothermolysis mediated by excited gold nanorod surface plasmons.

The photothermolysis of living EMT-6 breast tumor cells triggered by gold nanorods (AuNRs) with two-photon irradiation was conducted in situ and under real-time observation. The morphology and plasma membrane permeability of the cells were key indicators to the phenomena. AuNRs with an aspect ratio of 3.92, and a longitudinal absorption peak at 800 nm were synthesized with a seed-mediated method. The nanorods surfaces were further modified with polystyrenesulfonate (PSS) for biocompatibility. The prepared nanorods displayed excellent two-photon photoluminescence imaging. In situ real-time results revealed cavities internal to the cells were created from thermal explosions triggered by AuNRs localized photothermal effect. The cavitation dynamic is energy dependent and responsible for the perforation or sudden rupture of the plasma membrane. The energy threshold for cell therapy depended significantly on the number of nanorods taken up per cell. For an ingested AuNR cluster quantity N approximately 10-30 per cell, it is found that energy fluences E larger-than 93 mJ/cm(2) led to effective cell destruction in the crumbled form within a very short period. As for a lower energy level E = 18 mJ/cm(2) with N approximately 60-100, a non-instant, but progressive cell deterioration, is observed.

Doped spiral alumina nanowires.

Spiral alumina nanowires, doped with Cr and Si, are directly and reliably produced in bulk quantities via annealing of high entropy alloys.