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Actuation and Control of Droplets by Using Electrowetting-on-Dielectric

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Chinese Physics Letters 2004年第9期21卷 1851-1854页

作者：曾雪锋岳瑞锋吴建刚董良刘理天 instituteofmicroelectronics TsinghuaUniversityBeijing100084

Electrowetting-on-dielectric (EWOD) controls directly the wettability of liquids on the solid surface by applying an electric potential to the microelectrode array under the dielectric layer. A prototype of the EWOD droplet actuator is put forward, consisting of Si used as the substrate of the microelectrode array, Si3N4 film as the dielectric layer and fluorocarbon polymer (p-C:F) film deposited by plasma enhanced chemical vapour deposition (PECVD) as the hydrophobic layer. The p-C:F film was uniform and compact, and the contact angle of deionized water on the p-C:F film reached 110 degrees . The actuator successfully actuated deionized droplets surrounded in silicone oil at the voltage of 35V.

关键词： Electric potential

Chemical Sensors Based on Piezoresistive Cantilever Array

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Chinese Physics Letters 2003年第9期20卷 1637-1640页

作者：于晓梅张大成王丛舜杜先锋王小宝阮勇 instituteofmicroelectronics PekingUniversityBeijing100871

U-shaped and rectangle piezoresistive cantilever arrays have been designed with the analysing results of stress,noise and sensitivity of the cantilevers. Based on silicon micromachining technology, the piezoresistive cantilevers were fabricated by using polysilicon as the piezoresistive materials. With the measurement results of noise and sensitivity, the Hooge factor is cMculated to be 3×10^-3, the gauge factor is 27, and the minimum detectable deflection of piezoresistive cantilevers are calculated to be 1.0nm for rectangle cantilever and 0.5 nm for the Ushaped cantilever at a 6 V bias voltage and a 1000 Hz measurement bandwidth. Using polymer-coated cantilevers as individual sensors, their responses to water vapour and ammonia were tested by measuring their output voltage signals. The measured results show that the sensor sensitivity to ammonia can reach a few ppm and the sensor responses are quick.

关键词：化学传感器压阻悬臂阵列设计压力噪声灵敏性多晶硅压阻材料

Freestanding a-Si Thin Film Transistor for Room-Temperature Infrared Detection

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Chinese Physics Letters 2004年第2期21卷 262-265页

作者：董良岳瑞峰刘理天张万杰 instituteofmicroelectronics TsinghuaUniversityBeijing100084

We present the fabrication and characterization of a novel uncooled infrared sensor for room-temperature infrared imaging. The sensitive element of the sensor is a freestanding amorphous silicon thin film transistor (a-Si TFT) with the temperature coefficient of the drain current (TCC) of 0.015–0.08/K. The TCC value is sensitive to the ambient temperature and can be controlled by the gate voltage of the a-Si TFT. The complete procedures based on the porous silicon micromachining technique for fabricating thermally isolated air bridges are described. The isolation structures have a thermal conductance of 5×10−6W/K and a thermal capacitance of 4.9×10−8J/K. The effects of the gate voltage on the performance figures such as responsivity, noise voltage and detectivity are described and analysed in detail. The maximum detectivity reaches 4.33×108cmHz1/2W−1 at a chopping frequency of 27Hz and a gate voltage of -15V.

关键词： Drain current

Effect of Reverse Substrate Bias on Degradation of Ultra-Thin Gate-Oxide n-Channel Metal-Oxide-Semiconductor Field-Effect Transistors under Different Stress Modes

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Chinese Physics Letters 2005年第8期22卷 2127-2129页

作者：赵要许铭真谭长华 instituteofmicroelectronics PekingUniversityBeijing100871

Degradation of ultra-thin gate-oxide n-channel metal–oxide–semiconductor field-effect transistors with the halo structure has been studied under different stress modes with a reverse substrate bias. The device degradation under the same stress mode with different reverse substrate voltages has been characterized by monitoring the substrate current in a stressing process, which follows a simple power law. When the gate voltage is less than the critical value, the device degradation will first decrease and then increase with the increasing reverse substrate voltage, otherwise, the device degradation will increase continuously. The critical value can be obtained by measuring the substrate current variation with the increases of reverse substrate voltage and gate voltage. The experimental results indicate that the stress mode with enhanced injection efficiency and smaller device degradation can be obtained when the gate voltage is less than the critical value with a proper reverse substrate voltage chosen.

关键词： MOSFET CP CMOS

Characterization of Uncooled Poly SiGe Microbolometer for Infrared Detection

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Chinese Physics Letters 2003年第5期20卷 770-773页

作者： DONGLiang YUERui-Feng LIULi-Tian instituteofmicroelectronics TsinghuaUniversityBeijing100084

An uncooled poly SiGe microbolometer for infrared detection has been fabricated and characterized. The poly SiGe thin film is deposited by ultrahigh vacuum chemical vapour deposition (UHVCVD) system and its structural properties are characterized by Rutherford backscattering spectrometry (RBS) and Raman. The dependences of the temperature coefficient of resistance on operation temperature and on annealing temperature have been investigated. A leg-supported microbridge is used to decrease the thermal conductance of microbolometer with the silicon micromachining technique. The results show that at a chopping frequency of 15Hz and a bias voltage of 5V, the maximum detectivity of 8.3×108cm Hz1/2/W is achieved with a thermal response time of 16.6ms.

关键词：红外探测微辐射热计聚乙烯薄膜锗化硅 SiGe UHVCVD 超真空化学气相沉积卢瑟福散射光谱结构特征拉曼光谱硅显微机械加工技术

Investigation of Composition in Nano-Scaled Self-Assembled SiGe Islands

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Chinese Physics Letters 2005年第7期22卷 1761-1763页

作者：邓宁张磊陈培毅 instituteofmicroelectronics TsinghuaUniversityBeijing100084

A modified model is proposed to explain the influence of Si concentration on shape transition of self-assembled SiGe islands on Si substrates. The experimental results show that the critical sizes for shape transition from pyramids to domes (44, 50 and 60nm) increase with the increasing Si concentration (0.032, 0.09 and 0.17) from sample A to C. Based on the proposed model, the quantitative relation between the Si concentration and the critical size is established. Then the composition exactly in nano-scaled self-assembled SiGe islands is calculated from the measured critical size. The result shows that the Si concentration deduced from Raman spectrum is much larger than the actual values. It is demonstrated that the quantitative relation we obtained can be used to investigate the composition in nano-scaled SiGe islands.

关键词： composition scaled island

A Silicon—Based Ferroelectric Capacitor for Memory Devices

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Chinese Physics Letters 2002年第3期19卷 432-433页

作者：任天令张林涛等 instituteofmicroelectronics TsinghuaUniversityBeijing100084

We study a silicon-based PbTiO3/Pb(Zr0.53Ti0.47)O3/PbTiO3 capacitor, prepared by an improved sol-gel method. The ferroelectric capacitor has a high remanent polarization of 15µC/cm2 at a coercive field of about 30kV/cm, an ultra-low leakage current density of 0.1nA/cm2, and almost fatigue free properties. It can be used as a promising candidate for ferroelectric memory devices.

关键词： Sol-gel process

Comparison of neutron irradiation effects on the electrical performances of SiGe HBT and SiBJT

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Rare Metals 2003年第1期22卷 69-74页

作者： MENGXiangti WANGRuipian KANGAiguo WANGJilin JIAHongyong CHENPe instituteofmicroelectronics TsinghuaUniversityBeijing100084China InstituteofNuclearEnergyTechnology TsinghuaUniversityBeijing100084China

The change of electrical performances of silicon-germanium (SiGe)heterojunction bipolar transistor (HBT) and Si bipolar junction transistor (BJT) was studied as afunction of reactor fast neutron radiation fluence. Alter neutron irradiation, the collector currentI_c and the current gain beta decrease, and the base current I_b increases generally for SiGe HBT.The higher the neutron irradiation fluence is, the larger I_b increases. For conventional Si BJT,I_c and I_b increase as well as beta decreases much larger than SiGe HBT at the same fluence. It isshown that SiGe HBT has a larger anti-radiation threshold and better anti-radiation performance thanSi BJT. The mechanism of performance changes induced by irradiation was preliminarily discussed.

关键词： semiconductor technology SiGe HBT neutron irradiation Si BJT electrical performance

A Rigorous Investigation on the Ground State of the Penson—Kolb Model

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Communications in Theoretical Physics 2003年第5期39卷 607-612页

作者： YANGKai-Hua TIANGuang-Shan HANRu-Qi instituteofmicroelectronics PekingUniversityBeijing100871China SchoolofPhysics PekingUniversityBeijing100871CHina SchoolofPhysics PekingUniversityBeijing100871CHina instituteofmicroelectronics PekingUniversityBeijing100871China

By using either numerical calculations or analytical methods, such as the bosonization technique, the ground state of the Penson-Kolb model has been previously studied by several groups. Some physicists argued that, as far as the existence of superconductivity in this model is concerned, it is canonically equivalent to the negative-U Hubbard model.However, others did not agree. In the present paper, we shall investigate this model by an independent and rigorous approach. We show that the ground state of the Penson-Kolb model is nondegenerate and has a nonvanishing overlap with the ground state of the negative-U Hubbard model. Furthermore, we also show that the ground states of both the models have the same good quantum numbers and may have superconducting long-range order at the same momentum q ＝ 0. Our results support the equivalence between these models.

关键词：超导电性 Penson-Kolb模型强相关电子系统 “负-U Hubbard模型”