Jen-Chung Lou

Memory characteristics of Co nanocrystal memory device with HfO2 as blocking oxide

In this letter, the Co nanocrystals using SiO2 and HfO2 as the tunneling and the control dielectric with memory effect has been fabricated. A significant memory effect was observed through the electrical measurements. Under the low voltage operation of 5V, the memory window was estimated to ∼1V. The retention characteristics were tested to be robust. Also, the endurance of the memory device was not degraded up to 106 write/erase cycles. The processing of the structure is compatible with the current manufacturing technology of semiconductor industry.

Nickel nanocrystals with HfO2 blocking oxide for nonvolatile memory application

A distributed charge storage with Ni nanocrystals embedded in the SiO2 and HfO2 layer has been fabricated in this study. The mean size and aerial density of the Ni nanocrystals are estimated to be about 5nm and 3.9×1012∕cm2, respectively. The nonvolatile memory device with Ni nanocrystals exhibits 1V threshold voltage shift under 4V write operation. The device has a long retention time with a small charge lose rate. Besides, the endurance of the memory device is not degraded up to 106 write/erase cycles.

Using double layer CoSi2 nanocrystals to improve the memory effects of nonvolatile memory devices

The nonvolatile memory device with multilayer nanocrystals has advantages such as the memory effects can be increased by the increasing density of the nanocrystals and the whole retention characteristic can be improved. There are much more electrons that can be stored in the double layer than single layer nanocrystal memory device. The double layer CoSi2 nanocrystals have better retention characteristic than the single layer. The good retention characteristic of the double layer device is due to the Coulomb-blockage effects on the top layer nanocrystals from the bottom layer nanocrystals. So, the memory effects of the nonvolatile memory device can be improved by using the double layer nanocrystals.

Characterization of Oxygen Accumulation in Indium-Tin-Oxide for Resistance Random Access Memory

In this letter, we report the oxygen accumulation effect and its influence on resistive switching for gadolinium-doped silicon dioxide (Gd:SiO2) resistance random access memory (RRAM). We find that oxygen absorbance by indium-tin-oxide electrode affects the conduction current mechanism, and remarkably modifies the device performance of RRAM devices. By current fitting, Schottky emission can be observed in both low and high resistance states, from which conduction model is proposed to clarify the oxygen accumulation phenomenon. Reliability tests, including endurance and high temperature retention are further carried out, evaluating the significance of oxygen accumulation effect in redox reaction for RRAM devices.

Hopping effect of hydrogen-doped silicon oxide insert RRAM by supercritical CO 2 fluid treatment

In this letter, we introduced hydrogen ions into titanium metal doped into SiO2 thin film as the insulator of resistive random access memory (RRAM) by supercritical carbon dioxide (SCCO)2 fluid treatment. After treatment, low resistance state split in to two states, we find the insert RRAM, which means it has an operating polarity opposite from normal RRAM. The difference of the insert RRAM is owing to the resistive switching dominated by hydrogen ions, dissociated from OH bond, which was not by oxygen ions as usual. The current conduction mechanism of insert RRAM was hopping conduction due to the metal titanium reduction reaction through SCCO2.

Endurance Improvement Technology With Nitrogen Implanted in the Interface of

Incorporation of nitrogen as an oxygen-confining layer in the resistance switching reaction region is investigated to improve the reliability of resistance random access memory (RRAM). The switching mechanism can be attributed to the formation and rupture of conduction filaments. A compatible WSiON (around 5 nm) layer is introduced at the interface of tungsten silicon oxide (WSiOx) and TiN electrode to prevent the randomly diffusing oxygen ions surpassing the storage region of the WSiON layer. The double-layer WSiOx/WSiON memory structure would enhance the endurance over 100 times so as to better confirm the WSiOx RRAM application of nonvolatile memory.

{\rm WSiO}_{\bf x}

In this letter, the special role of hydrogen ions in hafnium doped silicon oxide resistive random access memory (RRAM) is presented. In addition to the more typical oxygen ion-dominated resistive switching, hydrogen ions were also observed to trigger a resistance transformation phenomenon, producing a tri-resistive device. Unlike a normal RRAM device, a hydrogen plasma-treated device is operated with a reversed voltage polarity, and the direction of hydrogen ion migration results in the chemical bonds breaking and repairing. By changing the voltage polarity and stop voltage, this tri-resistive behavior can be achieved. This particular hydrogen-induced switching behavior suggests a different RRAM switching mechanism and is finally explained by our model.

Resistance Switching Device

In this letter, one single-layer diamond-like carbon (DLC) resistive random access memory (RRAM) and two opposite stacking double-layer DLC/HfO2 RRAMs were prepared to investigate the resistance switching mechanism of DLC-based memristors. The RRAM devices were fabricated by sandwiching the active-layers between Pt top and TiN bottom electrodes. Based on the analyses for Pt/DLC/TiN and Pt/DLC/HfO2/TiN structures, we demonstrated the resistance switching in DLC RRAM is induced by hydrogen reaction near the Pt electrode. In addition, the resistance switching in Pt/HfO2/DLC/TiN structure is attributed to oxygen reaction near the TiN electrode. Based on the results of HfO2 stacked with DLC devices, we demonstrated for the first time the resistance switching of DLC at inactive electrode side (Pt) and active electrode side (TiN) is attributed to hydrogen and oxygen-induced redox of C-C bonds, respectively.

Tri-Resistive Switching Behavior of Hydrogen Induced Resistance Random Access Memory

Photosensitivity to ultraviolet (UV) light for zinc oxide (ZnO) resistance random access memory (RRAM) with transparent electrode was investigated and characterized in this paper. The resistive switching properties were affected severely through oxygen manipulation by UV light irradiation. To clarify the switching mechanism, conduction current fitting was applied and meanwhile a reaction model was proposed to explain the origin of drastic current variation. UV light-assisted oxygen manipulation in ZnO RRAM is an efficient method to modify device switching behavior, and this investigation also unveils the interesting phenomenon of transparent electrode RRAM under UV light illumination condition.

Resistance Switching Induced by Hydrogen and Oxygen in Diamond-Like Carbon Memristor

The formation of nickel-silicon-nitride nanocrystals by sputtering a comixed target in the argon and nitrogen environment is proposed in this letter. High resolution transmission electron microscope analysis clearly shows the nanocrystals embedded in the silicon nitride and x-ray photoelectron spectroscopy also shows the chemical material analysis of nanocrystals. The memory window of nickel-silicon-nitride nanocrystals enough to define 1 and 0 states is obviously observed, and a good data retention characteristic to get up to 10 years is exhibited for the nonvolatile memory application.