Qing Zhang

Bio: Qing Zhang is an academic researcher from University of California, Riverside. The author has contributed to research in topics: Gasoline & Capital cost. The author has an hindex of 3, co-authored 3 publications receiving 16 citations.

Write-Once–Read-Many-Times Memory Based on ZnO on p-Si for Long-Time Archival Storage

Abstract: Write-once-read-many-times memory cells were fabricated using ZnO thin film on p-Si (111) substrate. The off- and on-state resistance ratio is over 104 and can be well sustained for more than 100 years and perfectly endure reading cycles of 108 . The conducting filaments consisting of oxygen vacancies are responsible for the switching mechanism.

Metal/ZnO/MgO/Si/Metal Write-Once-Read-Many-Times Memory

Abstract: Write-once-read-many-times memory (WORM) devices were fabricated using ZnO and ZnO/MgO as active layers on Si. Devices fabricated with ZnO show a different memory effect at different current compliances such as WORM at 100 $\mu \text{A}$ , 500 $\mu \text{A}$ , and 1 mA, resistive switching (RS) instead of WORM at 5 and 10 mA, and WORM and RS coexisting at 20, 50, and 100 mA, while devices fabricated with ZnO/MgO show WORM only at all current compliances. A few nanometers of MgO layer play a major role in preventing devices from reset at all current compliances because the much lower drift velocity of oxygen vacancy in MgO and accumulation of negatively charged O2− ions at the interface between ZnO and MgO prevent the conducting filaments composed of oxygen vacancies from breaking.

The effect of top contact on ZnO write‐once–read‐many‐times memory

Abstract: Write-onceread-many-times memory (WORM) devices were fabricated using Ti/Au and Au as top contacts on ZnO thin films on Si. Electrical characterization shows that both types of WORM devices have large resistance OFF/ON ratio (R ratio), small resistance distribution range, long retention and good endurance. WORM devices with Au top contact have better performance of higher R ratio because of a larger work function of Au compared to Ti. ((c) 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Production of Fischer-Tropsch Synfuels at Nuclear Plants

Abstract: A case study analysis was performed to evaluate nuclear-powered synthetic fuel production in the midwestern United States (U.S.). A Fischer-Tropsch (FT) fuel synthesis plant design was used as the basis for the analysis. The FT plant design was configured to produce a product slate consisting of diesel fuel, jet fuel, and motor gasoline blend stocks from carbon dioxide (CO2) and hydrogen (H2) feedstocks. The CO2 feedstock for the FT plant was assumed to be sourced from biorefineries in the region around a Midwest light water reactor (LWR) nuclear power plant (NPP). The analysis specifies that power from the LWR is used to produce H2 via high-temperature steam electrolysis and to operate the FT synfuel production plant. Capital costs were estimated for the FT plant while capital costs for the electrolysis plant were based on previous Idaho National Laboratory (INL) studies. In addition to labor and maintenance costs for the FT and electrolysis plants, operating costs also include the costs for CO2 feedstock transport. An analysis was performed to determine the cost of transporting CO2 from the distributed biorefinery sources to the centralized fuel synthesis plant as a function of the synfuel plant capacity and corresponding CO2 demand. The primary revenue streams are associated with sales of the synthetic fuel products. The synthetic fuel products will likely follow the same market trends as the conventional fuel products. The synfuel price data was thus based on projections made by the U.S. Energy Information Administration (EIA) 2021 Annual Energy Outlook (AEO) for conventional fuel products minus federal and state taxes, as well as marketing and distribution costs. The economic analysis also considered cases that included and excluded revenues from the 2022 Inflation Reduction Act (IRA) clean hydrogen production tax credit (PTC) of $3.00/kg for the first ten years of operation. The economic analysis calculated the net present value (NPV) for cases involving steady-state synfuel production for comparison with the NPV for a business-as-usual case in which NPP continues to sell only electric power to the grid. A synfuel production “Reference Case” was considered in addition to sensitivity cases in which the plant capacity, electricity price, and synthetic fuel product prices were perturbed. The synfuel production Reference Case considered a scenario in which the electrolysis and synfuel plants utilized a combined electrical load of 1000 megawatt electrical (MWe) from the LWR with the balance of the LWR power output being sold to the electric grid. The economic analysis suggests that the synfuel production Reference Case evaluated in this analysis would lead to considerable economic potential for near-term deployment of a nuclear-based synfuel production plant. Specifically, the economic analysis suggests that the deployment of a 1000 megawatt (MW) nuclear-powered synfuel plant could result in a NPV increase of approximately $1.7 billion for a case with no clean synfuel price premium relative to conventional petroleum fuels when accounting for the additional revenues from the 2022 IRA clean hydrogen PTCs of $3/kg. Sensitivity analysis was performed to evaluate the effect of perturbation of selected model input parameters on the NPV for the synfuel production Reference Case. The sensitivity analysis indicates that the plant capacity has the largest impact on the differential NPV, with a smaller synfuel production capacity resulting in a decrease in revenue when a larger fraction of the power from the NPP is sold to the grid and a smaller fraction of the power is used to produce synthetic fuel products. The synfuel product pricing has the next largest impact on the differential NPV, with lower synfuel prices resulting in decreased NPV from decreased synfuel sales revenue while higher synfuel prices result in increased NPV from increased synfuel sales revenue. Electricity pricing has a smaller effect on the NPV than the fuel sales price since, in the Reference Case, most of the energy from the NPP is used for synfuel production and a smaller amount of the system revenues are associated with electrical power sales. However, the electricity price sensitivity does indicate that the Synfuel Integrated Energy System (IES) would have a greater NPV than the business-as-usual case (e.g., grid power sales only) when electricity market prices are low, suggesting that synfuel production could provide a strategy for decreasing the economic risks to NPPs posed by a loss of revenues attributed to falling electricity market prices.

A bio-inspired physically transient/biodegradable synapse for security neuromorphic computing based on memristors.

Abstract: Physically transient electronic devices that can disappear on demand have great application prospects in the field of information security, implantable biomedical systems, and environment friendly electronics. On the other hand, the memristor-based artificial synapse is a promising candidate for new generation neuromorphic computing systems in artificial intelligence applications. Therefore, a physically transient synapse based on memristors is highly desirable for security neuromorphic computing and bio-integrated systems. Here, this is the first presentation of fully degradable biomimetic synaptic devices based on a W/MgO/ZnO/Mo memristor on a silk protein substrate, which show remarkable information storage and synaptic characteristics including long-term potentiation (LTP), long-term depression (LTD) and spike timing dependent plasticity (STDP) behaviors. Moreover, to emulate the apoptotic process of biological neurons, the transient synapse devices can be dissolved completely in phosphate-buffered saline solution (PBS) or deionized (DI) water in 7 min. This work opens the route to security neuromorphic computing for smart security and defense electronic systems, as well as for neuro-medicine and implantable electronic systems.

Film-Nanostructure-Controlled Inerasable-to-Erasable Switching Transition in ZnO-Based Transparent Memristor Devices: Sputtering-Pressure Dependency

Abstract: We found that the write-once-read-many-times (WORM, inerasable)-to-rewritable (erasable) transition phenomenon results from the different structures of the filament, which is determined by the grain orientations of the deposited films. The conduction mechanism of this switching transition and its impact on the synaptic behavior in various ZnO nanostructures are also discussed. Furthermore, our WORM devices have a programmable physical damage function that can be exploited for use in security systems against data theft, hacking, and unauthorized use of software/hardware. This work proposes ZnO-based nonvolatile memory for invisible electronic applications and gives valuable insight into the design of WORM and rewritable memories.

Tunable Switching Characteristics of Low Operating Voltage Organic Bistable Memory Devices Based on Gold Nanoparticles and Copper Phthalocyanine Thin Films

Abstract: The influence of the top contact electrode on the switching characteristics of a low operating voltage organic bistable memory device, using copper phthalocyanine and gold nanoparticle thin films, was investigated using Au, Al, and Hg electrodes. While the ON/OFF ratio higher than 105 was achieved for all the devices, the nature of the memory behavior was found to be dependent on the top electrodes. Thermally evaporated Au and Al electrodes resulted in write-once–read-many times (WORM) behavior, whereas Hg drop soft contact led to write–read–erase–read (rewritable) characteristics, with the device retaining the ON state in the former and returning to the OFF state in the latter. The switching voltage was found to be influenced by the top electrode with the devices switching to the ON state at around 2 V for Hg and close to 1 V for Au and Al electrodes. Additionally, though the ON state conduction mechanism was dominated by Fowler–Nordheim (FN) tunneling through AuNP trap states in all the devices, the dyn...

Write-Once-Read-Many-Times and Bipolar Resistive Switching Characteristics of TiN/HfO 2 /Pt Devices Dependent on the Electroforming Polarity

Abstract: In this letter, we report the dependence of memory characteristics on electroforming polarity based on TiN/HfO2/Pt devices. Bipolar resistive switching (BRS) and write-once-read-many-times memory (WORM) behaviors were obtained after the negative and positive electroforming process, respectively. Analysis of conduction mechanisms of high resistance state confirms that BRS and WORM were dominated by Schottky emission and trap-controlled space charge limited current, respectively. These phenomena can be explained by the filamentary model with the assistance of interfacial role. Moreover, this letter also indicates that the TiN/HfO2/Pt devices have promising application in both RRAM and non-editable WORM.