Jian-Shiou Huang

Manipulated Transformation of Filamentary and Homogeneous Resistive Switching on ZnO Thin Film Memristor with Controllable Multistate

A bias polarity-manipulated transformation from filamentary to homogeneous resistive switching was demonstrated on a Pt/ZnO thin film/Pt device. Two types of switching behaviors, exhibiting different resistive switching characteristics and memory performances were investigated in detail. The detailed transformation mechanisms are systematically proposed. By controlling different compliance currents and RESET-stop voltages, controllable multistate resistances in low resistance states and a high resistance states in the ZnO thin film metal-insulator-metal structure under the homogeneous resistive switching were demonstrated. We believe that findings would open up opportunities to explore the resistive switching mechanisms and performance memristor with multistate storage.

Single CuOx Nanowire Memristor: Forming-Free Resistive Switching Behavior

CuOx nanowires were synthesized by a low-cost and large-scale electrochemical process with AAO membranes at room temperature and its resistive switching has been demonstrated. The switching characteristic exhibits forming-free and low electric-field switching operation due to coexistence of significant amount of defects and Cu nanocrystals in the partially oxidized nanowires. The detailed resistive switching characteristics of CuOx nanowire systems have been investigated and possible switching mechanisms are systematically proposed based on the microstructural and chemical analysis via transmission electron microscopy.

Bias enhanced nucleation and bias textured growth of diamond on silicon(100) in hot filament chemical vapor deposition

Abstract A four-step process, i.e. pretreatment, heating, bias nucleation and bias growth, was developed to enhance diamond nucleation and to grow textured diamond(100) on Si(100) in a hot filament chemical vapor deposition chamber. A polycrystalline diamond film was optimally nucleated on Si(100) during the period of nucleation enhancement via a bias of −250 V for approximately 30 min, with 1% of methane concentration in hydrogen flowing into the chamber. The nucleation density of diamond is approximately 107 cm−2. The uniform nucleation area is as large as 1.5 in. in diameter. A textured diamond(100) film was grown on the nucleated polycrystalline diamond film, simply by adding a bias of −50 V at the growth step. The capability of using negative bias to control the orientation of diamond grains in the hot filament chemical vapor deposition system is new to the diamond community.

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

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

Desegregation of boron at the grain boundaries of the in situ boron doped diamond films

High quality in situ boron doped polycrystalline diamond films were grown on the scratched Si (100) substrate. A saturated deionized water solution of boron acid was chosen as a dopant source. The concentration profiles of boron, tantalum, and oxygen were examined by using scanning Auger nanoprobe and secondary ion mass spectroscopy. The boron atoms are uniformly distributed inside each diamond grain. However, no Auger signal from boron was observed at grain boundaries within the detection limit. In contrast, tantalum atoms are uniformly distributed across diamond grains and grain boundaries. A simple model was proposed in explaining the boron desegregation.

Tunable Multilevel Storage of Complementary Resistive Switching on Single-Step Formation of ZnO/ZnWOx Bilayer Structure via Interfacial Engineering

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

Amorphous zinc-doped silicon oxide (SZO) resistive switching memory: manipulated bias control from selector to memristor

Manipulated bias control of a selector to a memristor was demonstrated in Zn-doped amorphous SiOx (SZO) films, within which ZnOx/Zn nanoclusters were segregated. For the selector, namely diode-like (pre-forming) switching, the threshold voltage varied from 9 to 2.7 V, with a resistance ratio of ∼104, by tuning the concentration of ZnOx/Zn nanoclusters. Stable bipolar resistive switching was achieved by current-controlled RESET and voltage-controlled SET processes. The working mechanism of the selector was explained by a transport mechanism which involved the “generalized trap-assisted tunnelling” of electrons resulting from doping with ZnOx/Zn nanoclusters. The dual-switching-mode of SZO provides a promising application for 3D cross-bar RRAM.

Roles of oxygen and nitrogen in control of nonlinear resistive behaviors via filamentary and homogeneous switching in an oxynitride thin film memristor

A TiOxNy thin film, which contains controllable concentrations of oxygen and nitrogen by a single-step reactive sputtering process using a non-symmetric Pt electrode as top electrode and TiN as bottom electrode, exhibiting non-linear I–V behavior, was proposed and demonstrated. A switching model of the non-linear I–V switching was built based on diffusion of oxygen vacancies in the TiOxNy film with different ratios of O and N after the SET process. Effects on the switching relationship between TiOxNy and electrodes were investigated to optimize the best conditions for the non-linear behavior. The origin of the nonlinear property was investigated in detail by changing the compositions of oxygen and nitrogen in the TiOxNy thin film. We believe that these findings would open up opportunities to exploit resistive switching mechanisms and simple memristor stacking in next generation crossbar array applications.

Reliability of Hall effect measurements on chemical vapor deposited polycrystalline B‐doped diamond films

In situ boron doped polycrystalline diamond films of very good quality were grown on both scratched n‐Si(100) and Al2O3 substrates. Carrier concentration and Hall mobility are mainly contributed from the n‐Si(100) substrate, rather than the boron doped polycrystalline diamond film, when n‐Si(100) is chosen as the substrate. This indicates that the p‐diamond/n‐Si junction is unable to isolate current flowing from the boron doped polycrystalline diamond to the n‐Si(100) substrate during Hall effect measurement. In contrast, carrier concentration and Hall mobility are reliable when Al2O3 is used as the insulating substrate for boron doped diamond deposition. The Hall mobility of the boron doped polycrystalline diamond film varies from 120 cm2/V s at a hole concentration of 1010/cm3 to 0.4 cm2/V s at 2×1015/cm3.

Spatial resolution of selectively deposited diamond stripes on ion implanted Si(100)

Diamond stripes were successfully grown on the P+ ion implanted Si(100) substrate without the diamond abrasives pretreatment. The pattern of a transmission line model (TLM) was used to define the shape of the diamond stripes on Si(100). Lateral resolution of diamond stripes depended on the thickness of SiO2 on the patterned Si(100) substrate. The width of each diamond stripe was about the same as that of the corresponding SiO2 open window for the SiO2 layer of 18 000 and 9000 A. A critical SiO2 thickness existed for diamond stripe deposition on the implanted Si(100), below which good spatial resolution of diamond stripes could not be achieved.