Nonvolatile Resistive Switching Memory Devices Research Articles

Air‐Stable Cesium Lead Iodide Perovskite for Ultra‐Low Operating Voltage Resistive Switching

AbstractCsPbX3 (X = halide, Cl, Br, or I) all‐inorganic halide perovskites (IHPs) are regarded as promising functional materials because of their tunable optoelectronic characteristics and superior stability to organic–inorganic hybrid halide perovskites. Herein, nonvolatile resistive switching (RS) memory devices based on all‐inorganic CsPbI3 perovskite are reported. An air‐stable CsPbI3 perovskite film with a thickness of only 200 nm is successfully synthesized on a platinum‐coated silicon substrate using low temperature all‐solution process. The RS memory devices of Ag/polymethylmethacrylate (PMMA)/CsPbI3/Pt/Ti/SiO2/Si structure exhibit reproducible and reliable bipolar switching characteristics with an ultralow operating voltage (<+0.2 V), high on/off ratio (>106), reversible RS by pulse voltage operation (pulse duration < 1 ms), and multilevel data storage. The mechanical flexibility of the CsPbI3 perovskite RS memory device on a flexible substrate is also successfully confirmed. With analyzing the influence of phase transition in CsPbI3 on RS characteristics, a mechanism involving conducting filaments formed by metal cation migration is proposed to explain the RS behavior of the memory device. This study will contribute to the understanding of the intrinsic characteristics of IHPs for low‐voltage resistive switching and demonstrate the huge potential of them for use in low‐power consumption nonvolatile memory devices on next‐generation computing systems.

Semiconductor-Free Nonvolatile Resistive Switching Memory Devices Based on Metal Nanogaps Fabricated on Flexible Substrates via Adhesion Lithography

Electronic memory cells are of critical importance in modern-day computing devices, including emerging technology sectors such as large-area printed electronics. One technology that has being receiving significant interest in recent years is resistive switching primarily due to its low dimensionality and nonvolatility. Here, we describe the development of resistive switching memory device arrays based on empty aluminum nanogap electrodes. By employing adhesion lithography, a low-temperature and large-area compatible nanogap fabrication technique, dense arrays of memory devices are demonstrated on both rigid and flexible plastic substrates. As-prepared devices exhibit nonvolatile memory operation with stable endurance, resistance ratios > $10^{4}$ and retention times of several months. An intermittent analysis of the electrode microstructure reveals that controlled resistive switching is due to migration of metal from the electrodes into the nanogap under the application of an external electric field. This alternative form of resistive random access memory is promising for use in emerging sectors such as large-area electronics as well as in electronics for harsh environments, e.g., space, high/low temperature, magnetic influences, radiation, vibration, and pressure.

Two-terminal nonvolatile resistive switching memory devices based on n-CdSe NR/p-Si heterojunctions

Two-terminal nonvolatile resistive switching (RS) memory devices based on n-CdSe nanoribbon (NR)/p-Si heterojunction were fabricated. These memory devices exhibited excellent memory characteristics with high current ON/OFF ratio exceeding six orders of magnitude, long retention time over 104 s, and good endurance over 6 months. The capacitance-voltage (C-V) measurement was carried out to confirm the electrons traping and detrapping processes in interface oxide layer. The high-performance of memory devices and simple processing techniques will offer new opportunities for memory applications of one-dimensional nanomaterials.

(Invited) ALD Grown Functional Oxide Layers for Nonvolatile Resistive Switching Memory Applications

The significance of atomic layer deposition (ALD) for the growth of transition metal oxide thin films which are to be integrated into metal-oxide-metal structures for future nonvolatile resistive switching memory devices is illustrated. Focus is put to the requirements on transition metal oxide layers with respect to the control of morphology, structure, and defect state. For the representative example of ALD TiO2-x thin films grown from different titanium sources possibilities for a design of thin film properties by means of precise process control are exemplified. The success of this strategy is highlighted by the resistive switching behavior of 8 nm ALD TiO2-x thin films integrated into Pt/ TiO2-x/Ti/Pt cross point junctions of 100 nm x 100 nm lateral size by which it could be demonstrated that a stable SET operation in TiO2 films is possible for compliance currents of about 20 µA.

Programmable complementary resistive switching behaviours of a plasma-oxidised titanium oxide nanolayer

Through the one-step plasma oxidation of TiN thin films at room temperature (a simple semiconductor technology compatible method), a partly oxidised structure of titanium oxynitride (TiN(x)O(y)) with a TiO(2-x) nanolayer on top has been prepared for non-volatile resistive switching memory devices. The fabricated Pt/TiO(2-x)/TiN(x)O(y)/TiN memory devices demonstrate complementary resistive switching behaviours within an operation voltage of 1 V. The complementary resistive switching behaviours can be explained by redistribution of the oxygen vacancies between the Pt/TiO(2-x) top interface and the TiO(2-x)/TiN(x)O(y) bottom interface in the TiO(2-x) nanolayer. A model concerning the resistive switching mechanism as well as a recover program of a failed device is also proposed. Our work provides a possible cost-efficient solution to suppress the sneak-path problem in nanoscale crossbar memory arrays.

Nonvolatile Memristive Switching Characteristics of TiO$_{\bm 2}$ Films Embedded With Nickel Nanocrystals

Nickel nanocrystal (Ni-NC)-embedded titanium dioxide films have been deposited for nonvolatile resistive switching memory devices. The polycrystalline behavior of the films has been observed from the X-ray diffraction spectra. Tiny isolated Ni-NCs with an average size of 4 nm are observed for the 1000 °C, 5-min annealed samples. Stable, bipolar, nonvolatile, and bistable resistive switching states are observed for the optimized annealed Ni-NC-embedded devices with a low SET and RESET voltage of 0.8 and −0.2 V, respectively. A high resistance ratio (>10 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$^3$</tex></formula> ), good stability, and retention properties are observed for the nanocrystal sample. The role of thin Ni-NC layer on memory switching stability is discussed.

Nonvolatile resistive switching characteristics of HfO2 with Cu doping

AbstractIn this work, resistive switching characteristics of hafnium oxide (HfO2) with Cu doping prepared by electron beam evaporation are investigated for nonvolatile memory applications. The top metal electrode/ hafnium oxide doped with Cu/n+ Si structure shows two distinct resistance states (high-resistance and low-resistance) in DC sweep mode. By applying a proper bias, resistance switching from one state to the other state can be achieved. Though the ratio of high/low resistance is less than an order, the switching behavior is very stable and uniform with nearly 100% device yield. No data loss is found upon continuous readout for more than 104 s. The role of the intentionally introduced Cu impurities in the resistive switching behavior is investigated. HfO2 films with Cu doping are promising to be used in the nonvolatile resistive switching memory devices.

Nonvolatile resistive switching memory utilizing gold nanocrystals embedded in zirconium oxide

Resistive switching characteristics of ZrO2 films containing gold nanocrystals (nc-Au) are investigated for nonvolatile memory applications. The sandwiched top electrode/ZrO2 (with nc-Au embedded)/n+ Si structure exhibits two stable resistance states (high-resistance state and low-resistance state). By applying proper voltage bias, resistive switching from one state to the other state can be achieved. This resistive switching behavior is reproducible and the ratio between the high and low resistances can be as high as two orders. The intentionally introduced nc-Au in ZrO2 films can improve the device yield greatly. ZrO2 films with gold nanocrystals embedded are promising to be used in the nonvolatile resistive switching memory devices.