蓝宝石衬底AlGaN/GaN HFET功率特性

通过台面隔离与注入隔离结合的方法,解决了由于GaN外延材料缓冲层质量差造成的AlGaN/GaN HFET击穿电压低的问题.通过优化的500℃/50s栅退火条件,改善Ni-AlGaN/GaN二极管特性,理想因子和势垒高度分别优化到1.5和0.87eV.通过改进AlGaN/GaN HFET制备工艺,得到提高器件输出功率的优化工艺,采用这一工艺制备的蓝宝石衬底总栅宽为1mm,器件在频率为8GHz时输出功率达到4.57W,功率附加效率为55.1%.     

AlGaN/GaN异质结场效应晶体管的阈值电压

利用AlGaN/GaN异质结场效应晶体管(AlGaN/GaN HFET)栅结构的电容-电压(C-V)特性确定AlGaN/GaN HFET的阈值电压.通过对模拟计算得到的AlGaN/GaN HFET电流-电压(I-V)特性曲线与测试得到的AlGaN/GaN HFET曲线比较分析,证实了依据AlGaN/GaN HFET栅结构的C-V特性曲线的微分极值点确定阈值电压是一种切实可行的方法.     

AlGaN/GaN异质结场效应晶体管的阈值电压

利用AlGaN/GaN异质结场效应晶体管(AlGaN/GaN HFET)栅结构的电容-电压(C-V)特性确定AlGaN/GaN HFET的阈值电压.通过对模拟计算得到的AlGaN/GaN HFET电流-电压(I-V)特性曲线与测试得到的AlGaN/GaN HFET曲线比较分析,证实了依据AlGaN/GaN HFET栅结构的C-V特性曲线的微分极值点确定阈值电压是一种切实可行的方法.     

跨导为325mS/mm的AlGaN/GaN HFET器件

报道了使用国产GaN外延材料（蓝宝石衬底）的AlGaN/GaN HFET器件的制备以及室温下器件的性能. 器件栅采用场板结构,其中栅长为0.3μm,场板长为0.37μm,源漏间距为3μm. 器件的饱和电流密度为0.572A/mm,最大漏电流密度为0.921A/mm,最大跨导为325mS/mm,由S参数外推出截止频率和最高振荡频率分别为27.9GHz和33.1GHz.     

跨导为325mS/mm的AlGaN/GaN HFET器件

报道了使用国产GaN外延材料(蓝宝石衬底)的AlGaN/GaN HFET器件的制备以及室温下器件的性能.器件栅采用场板结构,其中栅长为0.3μm,场板长为0.37μm,源漏间距为3μm.器件的饱和电流密度为0.572A/mm,最大漏电流密度为0.921A/mm,最大跨导为325mS/mm,由S参数外推出截止频率和最高振荡频率分别为27.9GHz和33.1GHz.     

采用PECVD方法制作SiO2绝缘层的AlGaN/GaN MOS-HFET器件

为了进一步减小栅漏电,提高击穿电压,将MOS结构的优点引入ALGaN／GaN HEMT器件中,研制并分析了新型的基于AlGaN／GaN的MOS—HFET结构。采用等离子增强气相化学沉积（PECVD）的方法生长了50nm的SiO2作为栅绝缘层,新型的AlGaN／GaN MOS—HFET器件栅长1μm,栅宽80μm,测得最大饱和输出电流为784mA／mm,最大跨导为44．25ms／mm,最高栅偏压＋6V。     

GaN基HFET电力电子器件的研究

作为第三代宽禁带半导体器件,GaN基HFET功率器件具耐高压、高频、导通电阻小等优良特性,在电力电子器件方面也具有卓越的优势。概述了基于电力电子方面应用的AlGaN/GaN HFET功率器件的研究进展。从器件的结构入手,介绍了AlGaN/GaN HEMT的研究现状,从栅材料的选取以及栅介质层的结构对器件性能的影响着手,对AlGaN/GaN MIS-HFET的研究进行了详细的介绍。分析了场板改善器件击穿特性的原理以及各种场板结构AlGaN/GaNHFET器件的研究进展。论述了实现增强型器件不同的方法。阐述了GaN基HFET功率器件在材料、器件结构、稳定性、工艺等方面所面临的挑战。最后探讨了GaN基HFET功率器件未来的发展趋势。     

凹栅AlGaN/GaN HFET

研究了总栅宽为100μm栅凹槽结构的AlGaN/GaN HFET,采用相同的外延材料,凹槽栅结构器件与平面栅结构器件比较其饱和电流变化小,跨导由260.3mS/mm增加到314.8mS/mm,n由2.3减小到1.7,栅极漏电减小一个数量级.在频率为8GHz时,负载牵引系统测试显示,当工作电压增加到40V,输出功率密度达到11.74W/mm.     

具有低欧姆接触电阻的高性能AlGaN/GaN HEMT器件研制

研究了AlGaN/GaN HEMT器件Ti/Al/Ti/Au四层金属结构欧姆接触的形成过程.通过系统研究退火条件获得了较低的欧姆接触电阻,实现了10-7Ω·cm2的欧姆接触率,并在此基础上对AlGaN/GaN HEMT欧姆接触形成机理进行了深入讨论.通过器件工艺的优化,研制了高性能的AlGaN/GaN HEMT器件.栅宽40μm的器件跨导达到250mS/mm,fT达到70GHz;栅宽0.8mm的功率器件电流密度达到1.07A/mm(Vg=0.5V),Vds=30V时,8GHz工作频率下(在片测试)器件的输出功率为32.5dBm(1.6W),输出功率密度达到2.14W/mm,功率增益为12.7dB.     

具有低欧姆接触电阻的高性能AlGaN/GaN HEMT器件研制

研究了AlGaN/GaN HEMT器件Ti/Al/Ti/Au四层金属结构欧姆接触的形成过程.通过系统研究退火条件获得了较低的欧姆接触电阻,实现了10-7Ω·cm2的欧姆接触率,并在此基础上对AlGaN/GaN HEMT欧姆接触形成机理进行了深入讨论.通过器件工艺的优化,研制了高性能的AlGaN/GaN HEMT器件.栅宽40μm的器件跨导达到250mS/mm,fT达到70GHz;栅宽0.8mm的功率器件电流密度达到1.07A/mm(Vg=0.5V),Vds=30V时,8GHz工作频率下(在片测试)器件的输出功率为32.5dBm(1.6W),输出功率密度达到2.14W/mm,功率增益为12.7dB.     

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.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

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.     

Critical Stage Rule-Based Real Time Dispatch（RTD）System in Highly-Mixed-Products （HMP） FAB

An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB.