Kai Huang Chen

Bipolar Switching Properties of the Manganese Oxide Thin Film RRAM Devices

Up to now, the various non-volatile memory devices such as, ferroelectric random access memory (FeRAM), magnetron random access memory (MRAM), and resistance random access memory (RRAM) were widely discussed and investigated. For these nonvolatile memory devices, the resistance random access memory (RRAM) devices will play an important role because of its non-destructive readout, low operation voltage, high operation speed, long retention time, and simple structure. The resistance random access memory (RRAM) devices were only consisting of one resistor and one corresponding transistor. The subject of this work was to study the characteristics of manganese oxide (MnO) thin films deposited on transparent conductive thin film using the rf magnetron sputtering method. The optimal sputtering conditions of as-deposited manganese oxide (MnO) thin films were the rf power of 80 W, chamber pressure of 20 mTorr, substrate temperature of 580°C, and an oxygen concentration of 40%. The basic mechanisms for the bistable resistance switching were observed. In which, the non-volatile memory and switching properties of the manganese oxide (MnO) thin film structures were reported and the relationship between the memory windows and electrical properties was investigated.

Processing and Electrical Properties of Ta and Li-Modified KNN-Based Lead-Free Thin Films Prepared by the RF Sputtering Technology

Lead-free potassium sodium niobate ceramic thin films were synthesized using rf magnetron sputtering technology for MFIS structures. The optimal sputtering parameters of the as-deposited KNN thin films for depositing times of 1h were obtained. Regarding the measured physical properties, the micro-structure and thickness of as-deposited KNN thin films for different oxygen concentration were obtained and compared by XRD patterns and SEM images. The surface roughness of KNN thin film was also observed by AFM morphology. The average grain size and root mean square roughness were 250 and 7.04 nm, respectively. For KNN thin films in the MFIS structure, the capacitance and leakage current density were 280 pF and 10-8A/cm2, respectively. We investigated that the leakage current density and the memory window increased, the capacitance critically increased as the oxygen concentration increased from 0 to 40%. However, the excess oxygen concentration process was decreased the electrical and physical of as-deposited KNN thin film. The effect of oxygen concentration on the physical and electrical characteristics of KNN thin films was investigated and determined.

Photoluminescence and Physical Properties of the Nano-Zn2SiO4:Mn Phosphor Powder under the Nitrogen Atmosphere

The subject of this work was to study the photoluminescence characteristics of nanoZnO and SiO2 powders into Zn2SiO4 phosphor, and to achieve better control on grain size and grain shape than traditional powder. The manganese elements were used to replace Zn2SiO4 defects and to achieve better control on grain size and grain shape than traditional powder. With different sintering atmosphere conditions, the effect of the photoluminescence intensity due to sintering temperature and the concentration of activator were be discussed by the X-Ray diffraction, SEM and TEM were utilized in the characterization of phase purity and microstructure of phosphor particles.

The Effect of Post-Conventional Thermal Annealing Process on the Photoluminescence Characteristics of Si+-Implanted SiO2 Thin Films

The shifted band and high intensity of the photoluminescence characteristics for RTA-treated Si+-implanted SiO2 thin films for 400-nm-thick thickness using post-CTA processing were discussed and investigated. The samples were treated in the temperature of 1150°C and 20s RTA processing under dry nitrogen atmosphere. The PL band of thin films obtained was 1.7 eV. However, the PL intensity of thin films was continuous decreased for RTA annealing time increased. In this study, the PL band for RTA-treated thin films using 1h post-CTA processing was shifted from 1.5 to 1.67 eV. In addition, the PL intensity of the thin films was increased under the post-CTA annealing time increased to 60s. From the plan-view of the HRTEM image, the Si nanocrystals of the RTA-treated thin films using post-CTA processing were observed. These results were related to the presence and variation of silicon Si nanocrystals embedded in thin films.

Fabrication and Switching Characterizations of Copper Oxide Thin Films for Applications in Resistive Random Access Memory Devices

Many nonvolatile memory devices such as, ferroelectric random access memory (FeRAM), magnetic random access memory (MRAM), ovonic universal memory (OUM), and resistive random access memory (RRAM) were considerable discussed and investigated. For these nonvolatile memory devices, the RRAM devices will play an important role because of its non-destructive readout, low operation voltage, high operation speed, long retention time, and simple structure. The RRAM devices were only consist of one resistor and one corresponding transistor. In this study, the CuO thin films deposited on ITO/glass and Pt/Ti/SiO2/Si substrates for applications in RRAM devices were produced and investigated. The optimal sputtering conditions of as-deposited CuO thin films were the rf power of 80 W, chamber pressure of 20 mTorr, substrate temperature of 580°C, and an oxygen concentration of 40%. The basic mechanisms for the bistable resistance switching were observed. The electrical and physics properties of CuO thin films for applications in RRAM devices were discussed.

Electrical and Physical Properties of (K0.5Na0.5)NbO3 Ferroelectric Thin Films

Lead-free potassium sodium niobate ceramic thin films were synthesized using rf magnetron sputtering technology for MFIS structures. The optimal sputtering parameters of the as-deposited KNN thin films for depositing times of 1h were obtained. Regarding the measured physical properties, the micro-structure and thickness of as-deposited KNN thin films for different oxygen concentration were obtained and compared by XRD patterns and SEM images. The surface roughness of KNN thin film was also observed by AFM morphology. The average grain size and root mean square roughness were 250 and 7.04 nm, respectively. For KNN thin films in the MFIS structure, the capacitance and leakage current density were 280 pF and 10-8A/cm2, respectively. We investigated that the leakage current density and the memory window increased, the capacitance critically increased as the oxygen concentration increased from 0 to 40%. However, the excess oxygen concentration process was decreased the electrical and physical of as-deposited KNN thin film. The effect of oxygen concentration on the physical and electrical characteristics of KNN thin films was investigated and determined.

Electrical Characteristics in Transparent (Bi3.25Nd0.75)(Ti2.9V0.1)O12 Ferroelectric Thin Films

In this study, we investigated the structure and ferroelectric properties of the as-deposited (Bi3.25Nd0.75)(Ti2.9V0.1)O12 ferroelectric thin films on ITO substrate fabricated by rf magnetron sputtering method. The electrical, ferroelectric and physical characteristics of as-deposited (Bi3.25Nd0.75)(Ti2.9V0.1)O12 thin films were developed under different conditions to find the optimal deposited parameters. The crystalline structure of the prepared (Bi3.25Nd0.75)(Ti2.9V0.1)O12 thin films was analyzed by X-ray diffraction (XRD). Field emission scanning electron microscopy (FESEM) was used to observe the film thickness and the surface morphology including grain size and porosity. Additionally, the remnant polarization of the as-deposited ferroelectric thin films was improved by neodymium and vanadium elements doped in this study. The remanent polarization of as-deposited ferroelectric thin films was 11 μC/cm2 as the measured frequency of 1kHz. Finally, the polarization of as-deposited ferroelectric thin film capacitor was decreased by 9% after the fatigue test with 109 switching cycles.

Electrical and Physical Properties of the Bi3.25La0.75Ti3O12 Ferroelectric Thin Films Prepared by Conventional Temperature Annealing Process

We have investigated the structure and ferroelectric properties of the Bi3.25La0.75Ti3O12 (BLT) thin films on SiO2/Si substrate fabricated by sol-gel method. We used the BLT films were annealed at various temperatures of 600, 650, and 700°C for one hour by conventional furnace annealing (CTA). The temperature dependence of leakage currents densities of ferroelectric BLT thin films. The crystalline structure of the prepared BLT thin films was analyzed by X-ray diffraction (XRD). Field emission scanning electron microscopy (FESEM) was used to observe the film thickness and the surface morphology including grain size and porosity. The leakage current density and capacitance of thin film were measured by HP4156C.

Effect of Pre-Calcined Method on Dielectric, Ferroelectric, and Piezoelectric Properties of Lead-Free Piezoelectric Lix(K0.5Na0.5)1-x(Nb0.8Ta0.2)O3 Ceramics

The structure and electrical characteristics of the lead-free Lix(K0.5Na0.5)1-x(Nb0.8Ta0.2)O3 (x=0~0.05) piezoelectric ceramics for the conventional solid-state reaction method and the B-side pre-calcined method were achieved and compared. For the B-side pre-calcined method, the lead-free ceramic material exhibited the excellent electrical and piezoelectric properties. The relative dielectric constant (εr) and loss (tan δ) of the Lix(K0.5Na0.5)1-x(Nb0.8Ta0.2)O3 for x=0.03 using the B-side pre-calcined method were 1223 and 0.021, respectively. In addition, the electromechanical coupling factors (kp) and Curie temperature (Tc) was 48.5 % and 315°C. Finally, the electrical properties of the lead-free Lix(K0.5Na0.5)1-x(Nb0.8Ta0.2)O3(x=0~0.05) homogeneity ceramics improved by the B-side pre-calcined method were also investigated and discussed.

Preparation and Characteristic Development of Nano Zn2SiO4: Mn Green Phosphors by La2O3 Doping

In this experimental, solid state method is used to synthesize proportioned nano-ZnO and SiO2 powders into Zn2SiO4 phosphor, and to achieve better control on grain size and grain shape than traditional powder. La is used to replace Mn; and to achieve better control on grain size and grain shape than traditional powder. With different sintering conditions, With different sintering conditions, the effect of the luminescent intensity due to sintering temperature and the concentration of activator would be discussed by the X-Ray Diffraction, SEM and TEM were utilized in the characterization of phase purity and microstructure of phosphor particles. Photoluminescence (PL) spectroscopy was utilized to characterize the optical properties. This use of phosphor materials is the application of the main light source, display components. Therefore, our study zinc silicate as the main principle of doping Mn, La of the characteristics of, expects to find the best glow.