AlGaN/GaN HEMT中电场分布的ATLAS模拟

用Silvaco的ATLAS软件模拟了栅场板参数对AlGaN/GaN HEMT中电场分布的影响.模拟结果表明,场板的加入改变了器件中电势的分布情况,降低了栅边缘处的电场峰值,改善了器件的击穿特性;场板长度(LFP,length of field plate)、场板与势垒层间的介质层厚度t等对电场的分布影响很大.随着LFP的增大、t的减小,栅边缘处的电场峰值Epeak1明显下降,对提高器件的耐压非常有利.通过对相同器件结构处于不同漏压下的情况进行模拟,发现当器件处于高压下时,场板的分压作用更加明显,说明场板结构更适合于制备用作电力开关器件的高击穿电压AlGaN/GaN HEMT.     

高耐压Si基GaN功率电子器件

基于Si基GaN HEMT材料制作了击穿电压530V、无场板的功率电子器件。器件制作工艺与现有GaN微波功率器件工艺兼容。研究了器件栅漏间距与击穿电压的关系。器件栅宽为100μm,栅漏间距为15μm时,得到的GaN HEMT器件击穿电压530V,最大电流密度536mA/mm。器件的特征通态电阻为1.54mΩ·cm2,是相同击穿电压Si MOSFET器件特征通态电阻的二十五分之一。所制作的6mm栅宽器件击穿电压400V,输出电流2A。该器件的研制为制作低成本GaN HEMT功率器件奠定了基础。     

X波段GaN HEMT内匹配器件

自主研制的GaN HEMT,栅源泄漏电流从10-4 A量级减小到了10 -6 A量级,有效提高了栅漏击穿电压,改善了器件工作特性.采用MIS结构制作了2.5mm栅宽GaN HEMT,测试频率为8GHz,漏源电压为33V时,器件连续波输出功率为18.2W,功率增益为7.6dB,峰值功率附加效率为43.0%.2.5mm×4 GaN HEMT内配配器件,测试频率8GHz,连续波输出功率64.5W,功率增益7.2dB,功率附加效率39%.     

X波段GaN HEMT内匹配器件

自主研制的GaN HEMT,栅源泄漏电流从1E-4A量级减小到了1E-6A量级,有效提高了栅漏击穿电压,改善了器件工作特性. 采用MIS结构制作了2.5mm栅宽GaN HEMT,测试频率为8GHz,漏源电压为33V时,器件连续波输出功率为18.2W,功率增益为7.6dB,峰值功率附加效率为43.0%. 2.5mm×4 GaN HEMT内匹配器件,测试频率8GHz,连续波输出功率64.5W,功率增益7.2dB,功率附加效率39%.     

3300V沟槽栅IGBT的衬底材料的优化设计

使用TCAD仿真软件对3 300 V沟槽栅IGBT的静态特性进行了仿真设计.重点研究了衬底材料参数、沟槽结构对器件击穿电压、电场峰值等参数的影响.仿真结果表明,随衬底电阻率增加,击穿电压增加,饱和电压和拐角位置电场峰值无明显变化;随衬底厚度增加,击穿电压增加,饱和电压增加,拐角位置电场峰值降低;随沟槽宽度增加,饱和电压降低,击穿电压和拐角位置电场峰值无明显变化;随沟槽深度增加,饱和电压降低,击穿电压无明显变化,拐角位置电场峰值增加;随沟槽拐角位置半径增加,击穿电压和饱和电压无明显变化,但拐角位置电场峰值减小.选择合适的衬底材料对仿真结果进行实验验证,实验结果与仿真结果相符,制备的IGBT芯片击穿电压为4 128 V,饱和电压约为2.18 V.     

5 W Si衬底GaN基HEMT研究

介绍了Si衬底上外延生长GaN基HEMT的制备及其直流特性与微波特性的研究结果:栅宽200 μm器件Vgs=0 V时饱和电流密度达0.975 A/mm,最大跨导240 mS/mm,夹断电压-4.5 V,栅漏击穿电压80 V;栅宽1 mm器件,在频率2 GHz下,工作电压Vds=25 V时,连续波输出功率为5.0 W,功率增益为9 dB,功率附加效率为35%.     

一种P-GaN栅结合混合帽层结构的HEMT器件

为了进一步提升P-GaN栅HEMT器件的阈值电压和击穿电压,提出了一种具有P-GaN栅结合混合掺杂帽层结构的氮化镓高电子迁移率晶体管(HEMT)。新器件利用混合掺杂帽层结构,调节整体极化效应,可以进一步耗尽混合帽层下方沟道区域的二维电子气,提升阈值电压。在反向阻断状态下,混合帽层可以调节栅极右侧电场分布,改善栅边电场集中现象,提高器件的击穿电压。利用Sentaurus TCAD进行仿真,对比普通P-GaN栅增强型器件,结果显示,新型结构器件击穿电压由593 V提升至733 V,增幅达24%,阈值电压由0.509 V提升至1.323 V。     

GaN基HEMT栅终端场板结构研究

制作了带有栅终端场板结构的GaN基HEMT,研究了击穿电压与场板长度的关系,提取了最佳场板长度为0.4,0.5,0.6μm时所对应的栅漏击穿电压最大,为120 V.研究了栅终端场板对器件小信号特性和大信号的影响,栅终端场板长度0.4μm时,器件特征频率及最大振荡频率减小量最小.在栅宽1 mm、频率8 GHz、无场板器件最大工作电压28 V时,连续波输出功率3.2 W,功率增益4.0 dB,功率附加效率17.0%;栅终端场板器件最大工作电压38 V时,连续波输出功率5.1 W,功率增益4.1 dB,功率附加效率21.0%.     

增强型AlGaN/GaN/AlGaN双异质结槽栅HEMT研究

为了在获得高击穿电压的同时实现增强型器件,对AlGaN/GaN/AlGaN双异质结HEMT进行了栅槽刻蚀,得到阈值电压为0.6 V的增强型HEMT。对器件特性的变化机理进行了分析,发现刻蚀引入的陷阱态使器件的击穿性能降低。采用变频电导法,定量研究了反应离子刻蚀在AlGaN/GaN/AlGaN双异质结HEMT中引入的陷阱态。研究表明,刻蚀工艺在双异质结HEMT中引入了大量的浅能级陷阱,这些陷阱的能级主要分布在0.36~0.40 eV。     

具有场板结构的AlGaN/GaN HEMT的直流特性

研制成功具有场板结构的AIGaN/GaN HEMT器件,对源场板、栅场板器件的性能进行了分析.场板的引入减小了器件漏电和肖特基漏电,提高了肖特基反向击穿电压.源漏间距4靘的HEMT的击穿电压由常规器件的65V提高到100V以上,肖特基反向漏电由37霢减小到5.7霢,减小了一个量级.肖特基击穿电压由常规结构的78V提高到100V以上.另外,还初步讨论了高频特性.     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.     

Teleportation of an arbitrary unknown N-qubit entangled state under the controlling of M controllers

A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers(M < N) is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home-Zeilinger (GHZ) state and N-M non-maximally entangled Einstein-Podolsky-Rosen (EPR) pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it.     

Diode-end-pumped Nd:YVO4/LBO lasers with 4.2W continuous-wave output at 457 nm

A continuous-wave (CW) 457 nm blue laser operating at the power of 4.2 W is demonstrated by using a fiber coupled laser diode module pumped Nd: YVO4 and using LBO as the intra-cavity SHG crystal With the optimization of laser cavity and crystal parameters, the laser operates at a very high efficiency. When the pumping power is about 31 W, the output at 457nm reaches 4.2 W, and the optical to optical conversion efficiency is about 13.5% accordingly. The stability of the out putpower is better than 1.2% for 8 h continuously working.     

Call for Papers

正Wireless Body-area Networks The last decade has witnessed the convergence of three giant worlds:electronics,computer science and telecommunications.The next decade should follow this convergence in most of our activities with the generalization of sensor networks.In particular with the progress in medicine,people live longer and the aging of population will push the development of wireless personal networks