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991.
TixSi1xOy (TSO) thin films are fabricated using plasma‐enhanced atomic layer deposition. The Ti content in the TSO films is controlled by adjusting the sub‐cycle ratio of TiO2 and SiO2. The refractive indices of SiO2 and TiO2 are 1.4 and 2.4, respectively. Hence, tailoring of the refractivity indices from 1.4 to 2.4 is feasible. The controllability of the refractive index and film thickness enables application of an antireflection coating layer to TSO films for use as a thin film solar cell. The TSO coating layer on an Si wafer dramatically reduces reflectivity compared to a bare Si wafer. In the measurement of the current‐voltage characteristics, a nonlinear coefficient of 13.6 is obtained in the TSO films. 相似文献
992.
Se-Ho Kim 《Microelectronic Engineering》2009,86(1):59-62
Microwave properties of Li-doped (Ba,Sr)TiO3 thick film interdigital capacitors have been investigated. According to the reported papers, BaSrTiO3 materials, paraelectric state at the room temperature, have high dielectric permittivity (>500 @ 1 MHz) and low loss tangent (<0.01 @ 1 MHz) in epitaxial thin film form; however, the sintering temperature of BaSrTiO3 is over 1350 °C. In order to reduce the sintering temperature, Li (3 wt%) was added to the BaSrTiO3 materials, and 10 μm thick Li-doped (Ba,Sr)TiO3 films were screen printed on the alumina (Al2O3) substrate and sintered at 900 °C. Interdigital capacitor patterns with five fingers of 200 μm gap and 250 μm length were also designed and fabricated by employing the screen printing method with Ag electrode. The structural feature was analyzed with X-ray diffraction method. Frequency and temperature-dependent dielectric properties were characterized from 1 kHz to 1 MHz and 303-403 K, respectively. Also, current-voltage characteristics were investigated with an elevated temperature. Microwave transmission and reflectance properties of thick film interdigital capacitors will be discussed, and frequency dispersion of dielectric properties will be presented. Specially, designed Au/Li-doped (Ba,Sr)TiO3/Ag-Pd/Al2O3 vertical structure was prepared to measure the tunability. In this sandwich type structure, Li-doped (Ba,Sr)TiO3 films showed tenability of 7.15% at a bias electric field of 20 kV/cm. 相似文献
993.
Successful pendeo-epitaxy growth of cubic silicon carbide (3C-SiC) on off-axis Si(001) substrates was achieved. The structural
and morphological characteristics of pendeo-epitaxy 3C-SiC were strongly affected by underlying stripes and seed layer thickness.
Stripes perpendicular to the Si substrate off-axis provide about three times faster lateral growth rate compared with parallel
oriented stripes. Root-mean-square (RMS) measurements using atomic force microscope (AFM) indicate that the surface morphology
of Pendeo-epitaxy 3C-SiC films remarkably improves with increasing seed layer thickness: from 9.8 nm for 3 μm thickness to 0.5 nm for 10 μm thickness. These effects on pendeo-epitaxy 3C-SiC are discussed with scanning electron microscopy (SEM) and AFM investigation. 相似文献
994.
Moon Gi Cho Kyung Wook Paik Hyuck Mo Lee Seong Woon Booh Tae-Gyu Kim 《Journal of Electronic Materials》2006,35(1):35-40
The interfacial reaction between 42Sn-58Bi solder (in wt.% unless specified otherwise) and electroless Ni-P/immersion Au was
investigated before and after thermal aging, with a focus on the formation and growth of an intermetallic compound layer,
consumption of under bump metallurgy (UBM), and bump shear strength. The immersion Au layer with thicknesses of 0 μm (bare
Ni), 0.1 μm, and 1 μm was plated on a 5-μm-thick layer of electroless Ni-P (with 14–15 at.% P). The 42Sn-58Bi solder balls
were then fabricated on three different UBM structures by using screen printing and pre-reflow. A Ni3Sn4 layer formed at the joint interface after the pre-reflow for all three UBM structures. On aging at 125°C, a quaternary phase,
identified as Sn77Ni15Bi6Au2, was observed above the Ni3Sn4 layer in the UBM structures that contain Au. The thick Sn77Ni15Bi6Au2 layer degraded the integrity of the solder joint, and the shear strength of the solder bump was about 40% less than the nonaged
joints. 相似文献
995.
We have demonstrated high-performance InGaN-GaN multiple quantum-wells light-emitting diodes (LEDs) using polarization-induced (PI) p-InGaN-GaN superlattice. Electrical measurements show that PI LEDs produce much lower series resistance and turn-on voltage (at 20 mA) as compared to those of normal LEDs without the superlattice. It is also shown that the output power and photon wavelength of the PI LEDs remain electrically stable up to a high stress region of 200 mA. However, those of normal LEDs become electrically and optically degraded in excess of 120 mA. These results show that the use of the PI effect is very effective to the improvement of the electrical properties of LEDs. 相似文献
996.
Dong Geon Lee Dong Hoe Kim Jae Myeong Lee Byeong Jo Kim Jun Young Kim Seong Sik Shin Hyun Suk Jung 《Advanced functional materials》2021,31(9):2006718
One of the most effective methods to achieve high-performance perovskite solar cells (PSCs) is to employ additives as crystallization agents or to passivate defects. Tri-iodide ion has been known as an efficient additive to improve the crystallinity, grain size, and morphology of perovskite films. However, the generation and control of this tri-iodide ion are challenging. Herein, an efficient method to produce tri-iodide ion in a precursor solution using a photoassisted process for application in PSCs is developed. Results suggest that the tri-iodide ion can be synthesized rapidly when formamidinium iodide (FAI) dissolved isopropyl alcohol (IPA) solution is exposed to LED light. Specifically, the photoassisted FAI–IPA solution facilitates the formation of fine perovskite films with high crystallinity, large grain size, and low trap density, thereby improving the device performance up to 22%. This study demonstrates that the photoassisted process in FAI dissolved IPA solution can be an alternative strategy to fabricate highly efficient PSCs with significantly reduced processing times. 相似文献
997.
Hong-Joon Yoon Dong-Min Lee Young-Jun Kim Sera Jeon Jae-Hwan Jung Sung Soo Kwak Jihye Kim SeongMin Kim Yunseok Kim Sang-Woo Kim 《Advanced functional materials》2021,31(23):2100649
Diverse touch experiences offer a path toward greater human–machine interaction, which is essential for the development of haptic technology. Recent advances in triboelectricity-based touch sensors provide great advantages in terms of cost, simplicity of design, and use of a broader range of materials. Since performance solely relies on the level of contact electrification between materials, triboelectricity-based touch sensors cannot effectively be used to measure the extent of deformation of materials under a given mechanical force. Here, an ion-doped gelatin hydrogel (IGH)-based touch sensor is reported to identify not only contact with an object but also deformation under a certain level of force. Switchable ionic polarization of the gelatin hydrogel is found to be instrumental in allowing for different sensing mechanisms when it is contacted and deformed. The results show that ionic polarization relies on conductivity of the hydrogels. Quantitative studies using voltage sweeps demonstrate that higher ion mobility and shorter Debye length serve to improve the performance of the mechanical stimuli-perceptible sensor. It is successfully demonstrated that this sensor offers dynamic deformation-responsive signals that can be used to control the motion of a miniature car. This study broadens the potential applications for ionic hydrogel-based sensors in a human–machine communication system. 相似文献
998.
Hui Dong Lee Chung-Hwan Kim Songcheol Hong 《Microwave and Wireless Components Letters, IEEE》2004,14(8):371-373
This paper describes a Tx module for IMT2000 applications consisting of an up-conversion mixer and a variable-gain driver amplifier. The up-conversion mixer, based on the Gilbert active topology has a power gain of 4.8 dB and consumes 15-mA current from a 3-V supply. The variable-gain driver amplifier comprises a gain-controlled stage of the current steering structure and a common emitter stage, and has a variable-gain range of over 30 dB with 30.3-mA current consumption. The Tx module achieves a gain error of less than 1.2 dB over a 30-dB gain range, an output IP3 of 25 dBm, and an output PI dB of 7.4 dBm at the maximum gain of 24.5 dB. It occupies 1.0 /spl times/ 1.2 mm. 相似文献
999.
The distributions of electric field and induced second‐order nonlinearity are analyzed in the periodic poling of optical fibers. A quasi‐phase matching efficiency for the induced nonlinearity is calculated in terms of both the electrode separation distance between the applied voltage and generalized electrode width for the periodic poling. Our analysis of the quasi‐phase matching efficiency implies that the conversion efficiency can be enhanced through adjusting the separation distance, and the electrode width can be maximized if the electrode width is optimized. 相似文献
1000.
In this paper, we design a rake‐based cellular radar receiver (CRR) scheme to detect a moving target located in a multipath environment. The modules of Doppler filter banks, threshold level test, and target detection module are newly introduced into the conventional rake receiver so that it can function as a radar system. The proposed CRR tests the Doppler‐shift frequency and signal‐to‐noise ratio of the received signal against predefined threshold levels to determine detection and then calculates target velocities and ranges. The system performance is evaluated in terms of detection probability and the maximum detection range under a Nakagami‐n channel that reflects the multipath environment. 相似文献