High‐mobility ZnO thin films are deposited onto solution‐processed ZrO2 dielectrics in order to investigate the large differences between experimental field‐effect mobility values obtained when transparent conductive oxide (TCO) materials are deposited onto high‐k dielectrics as opposed to thermally grown SiO2. Through detailed electrical characterization, the mobility enhancement in ZnO is correlated to the presence of electron traps in ZrO2 serving to provide an additional source of electrons to the ZnO. Furthermore, as a consequence of the general tendency for solution‐processed high‐k dielectrics to exhibit similar behavior, the broad applicability is suggested to other TCO/high‐k material combinations in agreement with experimental observations.

Additive patterning of transparent conducting metal oxides at low temperatures is a critical step in realizing low cost transparent electronics for display technology and photovoltaics. In this work, inkjet printed metal oxide transistors based on pure aqueous chemistries are presented. These inks readily convert to functional thin films at lower processing temperatures (T ≤ 250 °C) relative to organic solvent-based oxide inks, facilitating the fabrication of high-performance transistors with both inkjetprinted transparent electrodes of aluminum-doped cadmium oxide (ACO) and semiconductor (InO x ). The intrinsic fluid properties of these water-based solutions enable the printing of fine features with This article is protected by copyright. All rights reserved. 2 coffee-ring free line profiles and smoother line edges than those formed from organic solvent-based inks. The influence of low temperature annealing on the optical, electrical, and crystallographic properties of the ACO electrodes is investigated, as well as the role of aluminum doping in improving these properties. Finally, we characterize the all-aqueous printed TFTs with inkjet-patterned semiconductor (InO x ) and source/drain (ACO) layers, which show ideal low contact resistance (R c < 160 Ω-cm) and competitive transistor performance (µ lin up to 19 cm 2 V -1 s -1 , SS ≤ 150 mV dec -1 ) with only low temperature processing (T ≤ 250 °C).

Gravure printing is an attractive technique for patterning high-resolution features (<5 μm) at high speeds (>1 m/s), but its electronic applications have largely been limited to depositing nanoparticle inks and polymer solutions on plastic. Here, we extend the scope of gravure to a new class of materials and on to new substrates by developing viscous sol-gel precursors for printing fine lines and films of leading transparent conducting oxides (TCOs) on flexible glass. We explore two strategies for controlling sol-gel rheology: tuning the precursor concentration and tuning the content of viscous stabilizing agents. The sol-gel chemistries studied yield printable inks with viscosities of 20-160 cP. The morphology of printed lines of antimony-doped tin oxide (ATO) and tin-doped indium oxide (ITO) is studied as a function of ink formulation for lines as narrow as 35 μm, showing that concentrated inks form thicker lines with smoother edge morphologies. The electrical and optical properties of printed TCOs are characterized as a function of ink formulation and printed film thickness. XRD studies were also performed to understand the dependence of electrical performance on ink composition. Printed ITO lines and films achieve sheet resistance (Rs) as low as 200 and 100 Ω/□, respectively (ρ≈2×10(-3) Ω-cm) for single layers. Similarly, ATO lines and films have Rs as low as 700 and 400 Ω/□ with ρ≈7×10(-3) Ω-cm. High visible range transparency is observed for ITO (86-88%) and ATO (86-89%). Finally, the influence of moderate bending stress on ATO films is investigated, showing the potential for this work to scale to roll-to-roll (R2R) systems.

1 Introduction The low-cost arguments in support of printed electronics are strengthened by the potential for large-area, high-speed, roll-to-roll processing with high materials utilization in contrast to conventional processing techniques (i.e., photolithography) for applications utilizing low-end (i.e., lower performance) electronics [1]. To this end, there are several suitable printing-based manufacturing methods available (e.g., inkjet, gravure, screen-printing, aerojet, flexography, offset), each offering unique advantages and disadvantages. Roll-to-roll processing requires the use of materials processed at temperatures compatible with rollable/flexible substrates [2]. So far, organic materials have been successfully integrated into fully printed complex active devices and circuits (e.g., diodes, transistors, inverters, ring-oscillators, displays, radio frequency identification tags, and sensors) onto flexible substrates [3], likely due to the relatively low processing temperatures (<150 8C) required to optimize their performance and the maturity and flexibility of organic materials available. However, since organic materials are known to exhibit low field-effect mobility and poor air stability [4], there is a compelling reason to develop similar capability for higher performance inorganic materials such as transparent conductive oxides (TCOs), particularly for applications seeking to combine transparency, conductivity, and flexibility into novel technologies. In addition to their improved transparency, higher conductivity, improved stability, and higher

In neuromorphic computing, memristors (or “memory resistors”) have been primarily studied as key elements in artificial synapse implementations, where the memristor provides a variable weight with intrinsic long-term memory capabilities, based on its modifiable resistive-switching characteristics. Here, we demonstrate an efficient methodology for simulating resistive-switching of HfO2 memristors within Synopsys TCAD Sentaurus—a well established, versatile framework for electronic device simulation, visualization and modeling. Kinetic Monte Carlo is used to model the temporal dynamics of filament formation and rupture wherein additional band-to-trap electronic transitions are included to account for polaronic effects due to strong electron-lattice coupling in HfO2. The conductive filament is modeled as oxygen vacancies which behave as electron traps as opposed to ionized donors, consistent with recent experimental data showing p-type conductivity in HfOx films having high oxygen vacancy concentrations and ab-initio calculations showing the increased thermodynamic stability of neutral and charged oxygen vacancies under conditions of electron injection. Pulsed IV characteristics are obtained by inputting the dynamic state of the system—which consists of oxygen ions, unoccupied oxygen vacancies, and occupied oxygen vacancies at various positions—into Synopsis TCAD Sentaurus for quasi-static simulations. This allows direct visualization of filament electrostatics as well as the implementation of a nonlocal, trap-assisted-tunneling model to estimate current-voltage characteristics during switching. The model utilizes effective masses and work functions of the top and bottom electrodes as additional parameters influencing filament dynamics. Together, this approach can be used to provide valuable device- and circuit-level insight, such as forming voltage, resistance levels and success rates of programming operations, as we demonstrate.