Tunable Multilevel Storage of Complementary Resistive Switching on Single-Step Formation of ZnO/ZnWO_<i>x</i> Bilayer Structure via Interfacial Engineering

Tunable multilevel storage of complementary resistive switching (CRS) on single-step formation of ZnO/ZnWO_<i>x</i> bilayer structure via interfacial engineering was demonstrated for the first time. In addition, the performance of the ZnO/ZnWO_<i>x</i>-based CRS device with the voltage- and current-sweep modes was demonstrated and investigated in detail. The resistance switching behaviors of the ZnO/ZnWO_<i>x</i> 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 (<i>N</i>) 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

ZnO_1–<i>x</i> Nanorod Arrays/ZnO Thin Film Bilayer Structure: From Homojunction Diode and High-Performance Memristor to Complementary 1D1R Application

We present a ZnO_1–<i>x</i> nanorod array (NR)/ZnO thin film (TF) bilayer structure synthesized at a low temperature, exhibiting a uniquely rectifying characteristic as a homojunction diode and a resistive switching behavior as memory at different biases. The homojunction diode is due to asymmetric Schottky barriers at interfaces of the Pt/ZnO NRs and the ZnO TF/Pt, respectively. The ZnO_1–<i>x</i> NRs/ZnO TF bilayer structure also shows an excellent resistive switching behavior, including a reduced operation power and enhanced performances resulting from supplements of confined oxygen vacancies by the ZnO_1–<i>x</i> NRs for rupture and recovery of conducting filaments inside the ZnO TF layer. A hydrophobic behavior with a contact angle of ∼125° can be found on the ZnO_1–<i>x</i> NRs/ZnO TF bilayer structure, demonstrating a self-cleaning effect. Finally, a successful demonstration of complementary 1D1R configurations can be achieved by simply connecting two identical devices back to back in series, realizing the possibility of a low-temperature all-ZnO-based memory system

Single-Step Formation of ZnO/ZnWO_<i>x</i> Bilayer Structure via Interfacial Engineering for High Performance and Low Energy Consumption Resistive Memory with Controllable High Resistance States

A spontaneously formed ZnO/ZnWO_<i>x</i> 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 ZnWO_<i>x</i> 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 ZnWO_<i>x</i> layer, resulting in an asymmetric <i>I</i>–<i>V</i> 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/ZnWO_<i>x</i> bilayer structure with DC endurance >200 cycles for a possible application in three-dimensional multilayer stacking

A Molecular Triangle as a Precursor Toward the Assembly of a Jar-Shaped Metallasupramolecule

The reaction of Re₂(CO)₁₀ and 1,1′-carbonyldiimidazole in toluene afforded the molecular triangle [Re₃(μ₂-Im)₃(CO)₁₂] (<b>1</b>; Im = imidazolate). This air-stable complex <b>1</b> acted as a precursor, which could then be further transformed into the complex [{Re­(CO)₃}₃(μ₂-Im)₃(μ₃-L)] (<b>2</b>; L = 1,3,5-tris­(benzimidazol-1-ylmethyl)-2,4,6-trimethylbenzene) upon reaction with the flexible ligand L under solvothermal conditions. Complex <b>2</b> can also be produced directly in a one-pot reaction from Re₂(CO)₁₀, 1,1′-carbonyldiimidazole, and the flexible ligand L. A single-crystal X-ray diffraction analysis showed that compound <b>1</b> has a triangular-shaped structure, which is the smallest rhenium triangle known, as of this writing. Complex <b>2</b> adopted a jar-shaped structure. The photophysical properties of complexes <b>1</b> and <b>2</b> were studied

Direct Synthesis of Graphene with Tunable Work Function on Insulators via In Situ Boron Doping by Nickel-Assisted Growth

Work function engineering, a precise tuning of the work function, is essential to achieve devices with the best performance. In this study, we demonstrate a simple technique to deposit graphene on insulators with in situ controlled boron doping to tune the work function. At a temperature higher than 1000 °C, the boron atoms substitute carbon sites in the graphene lattice with neighboring carbon atoms, leading to the graphene with a p-type doping behavior. Interestingly, the involvement of boron vapor into the system can effectively accelerate the reaction between nickel vapor and methane, achieving a fast graphene deposition. The changes in surface potential and work function at different doping levels were verified by Kelvin probe force microscopy, for which the work function at different doping levels was shifted between 20 and 180 meV. Finally, the transport mechanism followed by the Mott variable-range hopping model was found due to the strong disorder nature of the system with localized charge-carrier states

A Molecular Triangle as a Precursor Toward the Assembly of a Jar-Shaped Metallasupramolecule

The reaction of Re₂(CO)₁₀ and 1,1′-carbonyldiimidazole in toluene afforded the molecular triangle [Re₃(μ₂-Im)₃(CO)₁₂] (<b>1</b>; Im = imidazolate). This air-stable complex <b>1</b> acted as a precursor, which could then be further transformed into the complex [{Re­(CO)₃}₃(μ₂-Im)₃(μ₃-L)] (<b>2</b>; L = 1,3,5-tris­(benzimidazol-1-ylmethyl)-2,4,6-trimethylbenzene) upon reaction with the flexible ligand L under solvothermal conditions. Complex <b>2</b> can also be produced directly in a one-pot reaction from Re₂(CO)₁₀, 1,1′-carbonyldiimidazole, and the flexible ligand L. A single-crystal X-ray diffraction analysis showed that compound <b>1</b> has a triangular-shaped structure, which is the smallest rhenium triangle known, as of this writing. Complex <b>2</b> adopted a jar-shaped structure. The photophysical properties of complexes <b>1</b> and <b>2</b> were studied

A Molecular Triangle as a Precursor Toward the Assembly of a Jar-Shaped Metallasupramolecule

The reaction of Re₂(CO)₁₀ and 1,1′-carbonyldiimidazole in toluene afforded the molecular triangle [Re₃(μ₂-Im)₃(CO)₁₂] (<b>1</b>; Im = imidazolate). This air-stable complex <b>1</b> acted as a precursor, which could then be further transformed into the complex [{Re­(CO)₃}₃(μ₂-Im)₃(μ₃-L)] (<b>2</b>; L = 1,3,5-tris­(benzimidazol-1-ylmethyl)-2,4,6-trimethylbenzene) upon reaction with the flexible ligand L under solvothermal conditions. Complex <b>2</b> can also be produced directly in a one-pot reaction from Re₂(CO)₁₀, 1,1′-carbonyldiimidazole, and the flexible ligand L. A single-crystal X-ray diffraction analysis showed that compound <b>1</b> has a triangular-shaped structure, which is the smallest rhenium triangle known, as of this writing. Complex <b>2</b> adopted a jar-shaped structure. The photophysical properties of complexes <b>1</b> and <b>2</b> were studied

A Molecular Triangle as a Precursor Toward the Assembly of a Jar-Shaped Metallasupramolecule

The reaction of Re₂(CO)₁₀ and 1,1′-carbonyldiimidazole in toluene afforded the molecular triangle [Re₃(μ₂-Im)₃(CO)₁₂] (<b>1</b>; Im = imidazolate). This air-stable complex <b>1</b> acted as a precursor, which could then be further transformed into the complex [{Re­(CO)₃}₃(μ₂-Im)₃(μ₃-L)] (<b>2</b>; L = 1,3,5-tris­(benzimidazol-1-ylmethyl)-2,4,6-trimethylbenzene) upon reaction with the flexible ligand L under solvothermal conditions. Complex <b>2</b> can also be produced directly in a one-pot reaction from Re₂(CO)₁₀, 1,1′-carbonyldiimidazole, and the flexible ligand L. A single-crystal X-ray diffraction analysis showed that compound <b>1</b> has a triangular-shaped structure, which is the smallest rhenium triangle known, as of this writing. Complex <b>2</b> adopted a jar-shaped structure. The photophysical properties of complexes <b>1</b> and <b>2</b> were studied

Large Scale and Orientation-Controllable Nanotip Structures on CuInS₂, Cu(In,Ga)S₂, CuInSe₂, and Cu(In,Ga)Se₂ by Low Energy Ion Beam Bombardment Process: Growth and Characterization

One-step facile methodology to create nanotip arrays on chalcopyrite materials (such as CuInS₂, Cu­(In,Ga)­S₂, CuInSe₂, and Cu­(In,Ga)­Se₂) via a low energy ion beam bombardment process has been demonstrated. The mechanism of formation for nanotip arrays has been proposed by sputtering yields of metals and reduction of metals induced by the ion beam bombardment process. The optical reflectance of these chalcopyrite nanotip arrays has been characterized by UV–vis spectrophotometer and the efficient light-trapping effect has been observed. Large scale (∼4′′) and high density (10¹⁰ tips/cm²) of chalcopyrite nanotip arrays have been obtained by using low ion energy (< 1 kV), short processing duration (< 30 min), and template-free. Besides, orientation and length of these chalcopyrite nanotip arrays are controllable. Our results can be the guide for other nanostructured materials fabrication by ion sputtering and are available for industrial production as well