Enhanced light extraction of GaN-based light-emitting diodes with periodic textured SiO_2 on Al-doped ZnO transparent conductive layer

We report an effective enhancement in light extraction of Ga N-based light-emitting diodes（LEDs） with an Al-doped Zn O（AZO） transparent conductive layer by incorporating a top regular textured SiO2 layer. The 2 inch transparent throughpore anodic aluminum oxide（AAO） membrane was fabricated and used as the etching mask. The periodic pore with a pitch of about 410 nm was successfully transferred to the surface of the SiO2 layer without any etching damages to the AZO layer and the electrodes. The light output power was enhanced by 19% at 20 m A and 56% at 100 m A compared to that of the planar LEDs without a patterned surface. This approach offers a technique to fabricate a low-cost and large-area regular pattern on the LED chip for achieving enhanced light extraction without an obvious increase of the forward voltage.

INFLUENCE OF MAGNETIC FIELD ON ACCURACY OF ECM BY CHANGING THE CONDUCTIVITY OF ANODE FILM

The change of conductivity, thickness and scanning electron microscopy （SEM） appearance of the anode film of CrWMn in 10% NaNO3 at different anode potential either with or without the magnetic field applied are investigated by testing film resistance, galvanostatic transient and using SEM to design magnetic circuit in magnetic assisted electrochemical machining （MAECM）. The experiments show that the anode film has semi-conducting property. Compared with the situation without magnetic field applied, the resistance of the film formed at 1 .SV （anode potential） increased and decreased at 4.0V while B=0.4T and the magnetic north pole points toward anode. The SEM photo demonstrates that the magnetic field will densify the film in the passivation area and quicken dissolution of the anode metal in over-passivation area. Based on the influence of magnetic field on electrochemical machining（ECM） due to the changes of the anode film conductivity behavior, the magnetic north pole should be designed to point towards the workpiece surface that has been machined. Process experiments agree with the results of test analysis.

EXPERIMENT AND RESEARCH ON DEVELOPMENT AND CHARACTERIZATIONS OF ANODIC ALUMINA MEMBR-ANE FOR USE IN HEMODIALYSIS

Objective The correlation between various formative conditions and the pore characterizationsof the anodic alumina membrane is investigated to seek the optimal conditions for the formation of anodic aluminamembrane. Methods High purity aluminum foils are used as the starting materials. The anodization is conduc-ted in three types of electrolytes, 3% sulfuric acid, 5% sulfuric acid and 2. 7% oxalic acid, respectively, with dif-ferent voltages at for 48h. The characterizations of the pore size, the effective porosity and the pore porosity areobserved and determined by scanning electron microscopy. The hydraulic conductances of the membranes are meas-ured to confirm that the pores are open and evaluate the permselectivity of the membranes. Results The experi-mental result shows that the ordered pore arrays are obtained for oxidation under our experimental conditions. Withthe increasing of the voltage, the pore size and pore porosity increased significantly (P <0.05) , while the effectiveporosity decreased significantly (P <0.05) with the same electrolyte. The pore size formed in 3% sulfuric acid or5% sulfuric acid is much smaller than in 2. 7% oxalic acid as an electrolyte. The hydraulic conductance of anodicalumina membrane that formed under our experimental condition is higher than those of the membranes are availablecurrently used in clinical. Conclusion The results suggest that the optimal conditions for the formation of anodicalumina membrane that used in hemodialysis are in 3% or 5% sulfuric acid with 12. 5V to 17. 5V at for 48h.

Theoretical investigation of frequency characteristics of free oscillation and injection-locked magnetrons

The frequency characteristics of free oscillation magnetron（FOM） and injection-locked magnetron（ILM） are theoretically investigated.By using the equal power voltage obtained from the experiment data,expressions of the frequency and radio frequency（RF） voltage of FOM and ILM,as well as the locking bandwidth,on the anode voltage and magnetic field are derived.With the increase of the anode voltage and the decrease of the magnetic field,the power and its growth rate increase,while the frequency increases and its growth rate decreases.The theoretical frequency and power of FOM agree with the particle-in-cell（PIC） simulation results.Besides,the theoretical trends of the power and frequency with the anode voltage and magnetic field are consistent with the experimental results,which verifies the accuracy of the theory.The theory provides a novel calculation method of frequency characteristics.It can approximately analyze the power and frequency of both FOM and ILM,which promotes the industrial applications of magnetron and microwave energy.

Synthesis and properties of ionic conduction polymer for anodic bonding

In this study,powders of polyethylene oxide（PEO） and lithium perchlorate（Li Cl O4） were used as the raw materials for producing the ionic conduction polymer PEO–Li Cl O4 with different complex-ratios and used for anodic bonding through high energy ball milling method,and meanwhile,X-ray diffraction,differential scanning calorimetry（DSC）,ultraviolet absorption spectrum test analysis,and other relevant methods were adopted to research the complexation mechanism of PEO and Li Cl O4 and the impact of the ionic conduction polymer with different complex-ratios on the anodic bonding process under the action of the strong static electric field.The research results showed that the crystallization of PEO could be effectively obstructed with increased addition of Li Cl O4,thus increasing the content of PEO–Li Cl O4 in amorphous area and continuously improving the complexation degree and the room-temperature conductivity thereof,and that the higher room-temperature conductivity enabled PEO–Li Cl O4 to better bond with metallic aluminum and have better bonding quality.As the new encapsulating material,such research results will promote the application of new polymer functional materials in micro-electromechanical system（MEMS） components.

Effect of carbon nanotubes addition on electrochemical performance and thermal stability of Li_4Ti_5O_(12) anode in commercial Li Mn_2O_4/Li_4Ti_5O_(12) full-cell

Li4Ti5O12（LTO）/carbon nanotubes（CNTs） composite material is synthesized based on a solid-state method by sand-milling, spray-drying and calcining at 850 8C under N2 flow. The LTO/CNTs samples with1 wt% and 3 wt% weight ratio of CNTs addition and the pristine LTO sample are prepared. The rate performance and the thermal stability of these samples are investigated based on Li Mn2O4（LMO）/LTO full-cell. The results show that the weight ratio of CNTs addition has distinct effect on LTO performances.The composite materials of LTO composited CNTs have better performance at high-rate due to the intercalation enhancement by conductive network of CNTs. At second, the overcharging temperature response of the cell＇s surface with 1 wt% CNTs addition is the lowest. The particle size distribution is measured and the most uniform particles are obtained with 1 wt% CNTs addition. This trend could explain that the medium quantity of CNTs is optimal to improve the heat and mass transfer and prevent the problems of crystallite growing interference and aggregation during the calcination process.