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.

Design Concept for Key Parameters of Reverse Conducting GCT

Presented is design concept for key parameters o f the reverse conducting gate commutated thyristor (RC-GCT),such as the thickness and concentration of n-base region and the transparent anode region,and the wi dth of separation region between asymmetric GCT and PIN diode.A structure model of the RC-GCT is set up based on the design concept and its characteristics are analyzed.The simulation results show the design concept is reasonable.

Effects of transparent MPTMS/Ag/MoO_3 structure as anode on the performance of green organic light-emitting diodes

A transparent 3-mercaptopropyl trimethoxysilane(MPTMS)/Ag/MoO3 composite anode is introduced to fabricate green organic light-emitting diodes(OLEDs). Effects of the composite anode on brightness and operating voltage of OLEDs are researched. By optimizing the thickness of each layer of the MPTMS/Ag/MoO3 structure, the transmittance of MPTMS/Ag(8 nm)/Mo O3(30 nm) reaches over 75% at about 520 nm. The sheet resistance is 3.78 ?/□, corresponding to this MPTMS/Ag(8 nm)/MoO3(30 nm) structure. For the OLEDs with the optimized anode, the maximum electroluminescence(EL) current efficiency reaches 4.5 cd/A, and the maximum brightness is 37 036 cd/m2. Moreover, the OLEDs with the optimized anode exhibit a very low operating voltage(2.6 V) for obtaining brightness of 100 cd/m2. We consider that the improved device performance is mainly attributed to the enhanced hole injection resulting from the reduced hole injection barrier height. Our results indicate that employing the MPTMS/Ag/MoO3 as a composite anode can be a simple and promising technique in the fabrication of low-operating voltage and high-brightness OLEDs.

Simulation of Secondary Electron and Backscattered Electron Emission in A6 Relativistic Magnetron Driven by Different Cathode

Prticle-in-cell（PIC） simulations demonstrated that,when the relativistic magnetron with diffraction output（MDO） is applied with a 410 kV voltage pulse,or when the relativistic magnetron with radial output is applied with a 350 kV voltage pulse,electrons emitted from the cathode with high energy will strike the anode block wall.The emitted secondary electrons and backscattered electrons affect the interaction between electrons and RF fields induced by the operating modes,which decreases the output power in the radial output relativistic magnetron by about 15%（10%for the axial output relativistic magnetron）,decreases the anode current by about 5%（5%for the axial output relativistic magnetron）,and leads to a decrease of electronic efficiency by 8%（6%for the axial output relativistic magnetron）.The peak value of the current formed by secondary and backscattered current equals nearly half of the amplitude of the anode current,which may help the growth of parasitic modes when the applied magnetic field is near the critical magnetic field separating neighboring modes.Thus,mode competition becomes more serious.

Effect of Al:Ag alloy cathode on the performance of transparent organic light-emitting devices

Transparent organic light-emitting devices(TOLEDs) based on a stacked alloy cathode of LiF/Al:Ag are investigated. The devices have a structure of indium-tin-oxide(ITO)/4,4′,4′′-Tris[2-naphthyl(phenyl)amino]triphenylamine(2T-NATA)(25 nm)/N,N'-Di-[(1-naphthyl)-N,N'-diphenyl]-1,1'-biphenyl-4,4'-diamine(NPB)(40 nm)/tris-(8-hydroxyquinoline) aluminum(Al_(q_3))(50 nm)/LiF(1 nm)/Al:Ag(1:3)(x), where the thicknesses of cathode metal layers(Al:Ag) are adjusted, respectively, from 70 nm to 100 nm. In the experiment, it is found that the Li F(1 nm)/Al:Ag(1:3)(75 nm) has good electron injection efficiency. Compared with an Al-only cathode, the turn-on voltage is lowered. At the voltage of 10 V, the luminances for bottom emission from ITO anode side and top emission from metal cathode side are 2 459 cd/m^2 and 1 729 cd/m^2, respectively. Thanks to electron injection enhancement by using Al:Ag cathode, we can obtain a better energy level matching between the cathode and the organic layer, thus the devices have lower turn-on voltage and higher luminance. The total transmittance of the devices can achieve about 40% at the wavelength of 550 nm.