高k栅介质小尺寸双栅GeOI MOSFET电特性 模拟及结构优化

The influences of the main structure and physical parameters of the dual-gate GeOl MOSFET on the device performance are investigated by using a TCAD 2D device simulator. A reasonable value range of germanium （Ge） channel thickness, doping concentration, gate oxide thickness and permittivity is determined by analyzing the on-state current, off-state current, short channel effect （SCE） and drain-induced barrier lowering （DIBL） effect of the GeOI MOSFET. When the channel thickness and its doping concentration are 10-18 nm and （5-9）×1017 cm-3, and the equivalent oxide thickness and permittivity of the gate dielectric are 0.8-1 nm and 15-30, respectively, excellent device performances of the small-scaled GeOI MOSFET can be achieved： on-state current of larger than 1475 μA/μm, off-state current of smaller than 0.1μA/μm, SCE-induced threshold-voltage drift of lower than 60 mV and DIBL-induced threshold-voltage drift of lower than 140 mV.     

Design of MCI single and symmetrical on-chip spiral inductors

In this paper, the MCI (multipath crossover interconnection) technique for octagon single and symmetrical spiral inductors has been presented to improve the quality factor. The metal wires of the single and symmetrical inductors formed by the top metal are divided into multiple segments according to the depth of the skin effects. The outermost path of the metal is crossover-interconnected to the innermost path by the underlayer metal and via The crossover technique makes the lengths of the total current paths between two ports approximately equal to each other. Therefore, the induced magnetic flux and resistance of each path can be balanced and the Q-factor of spiral inductors can be enhanced. The proposed MCI technique has been validated by the electromagnetic simulation with the 130-nm 1P6M SiGe BiCMOS process. For the devices with occupying areas of 240×240μm², results of electromagnetic simulation show that about 24% improvement in the Q-peak (3.3 GHz) of the MCI single inductor as compared to conventional single inductors (3.1 GHz), and about 88.1% improvement in the Q-peak (3.2 GHz) of the MCI symmetrical inductor as compared to conventional symmetrical inductors (1.8 GHz).     

dV/dt effect in high-voltage (1.5 kV) 4H–SiC thyristors

The switching of high-voltage (1.5 kV) 4H–SiC gate turn-off thyristors (GTOs) by the dV/dt effect has been studied in the temperature range from 300 to 504 K. At a 30 ns rise time of the forward bias V(t), the characteristic bias at which the structure under investigation can be switched on by the dV/dt effect decreases steadily from 289 V at room temperature (dV/dt 9.7 kV/μs) to 137 V at T = 504 K. The characteristic critical charge per unit area, Q_cr, equal to 1.9 × 10⁻⁷ C/cm² at room temperature, also decreases steadily as the temperature increases. The main physical mechanisms that contribute to Q_cr formation and the temperature dependence of the critical charge are qualitatively analyzed. The influence exerted by two-dimensional processes on the dV/dt switching is examined by making analytical estimates and using a computer simulation. The results obtained agree well with experimental data.     

小尺寸堆栈高k栅介质GaAs nMOSFET阈值电压模型

通过求解沟道的二维泊松方程,建立了小尺寸高k栅介质GaAs MOSFET的阈值电压模型．模型包括了短沟道效应、漏致势垒降低效应和量子效应．模拟结果与TCAD仿真结果符合较好,证实了模型的正确性和实用性．利用该模型,分析了堆栈高k栅介质结构及其物理参数对阈值电压漂移的影响以及阈值电压的温度特性．结果表明,堆栈栅介质结构能有效抑制边缘场和DIBL效应,改善MOSFET的阈值特性和温度特性;未考虑量子效应的模型过高估计了温度对阈值电压的影响。     

超薄EOT高K金属栅结构中串联电阻效应对瞬时击穿特性的影响

本文研究了超薄EOT高K金属栅MOS电容结构的瞬时击穿特性。由于串联电阻效应的影响，MOS电容的瞬时击穿特性的面积依赖关系与理论推导不符。器件中的串联电阻可以通过对IV特性的FN拟合得到。在本文的器件结构中，经验证得到串联电阻主要是由于电极的不对称性引起的扩展电阻。本文提出一种采用串联模型对击穿分布特性进行修正的方法。修正后的瞬时击穿特性与面积的依赖关系符合泊松面积归一规律，这说明对于超薄EOT的高K金属栅结构，瞬时击穿的机制与时变击穿的机制相同，都是由缺陷产生过程导致的击穿过程。     

Hall effect analysis of high purity p-type GaAs grown by metalorganic chemical vapor deposition

Variable temperature Hall effect and low temperature photoluminescence measurements have been performed on high purityp- andn-type GaAs grown at atmospheric pressure by metalorganic chemical vapor deposition. These high purity epitaxial GaAs layers were grown as a function of the arsine (AsH₃) to trimethylgallium (TMG) ratio (V/III ratio). The accurate quantitative assessment of the electronic properties of thep-type layers was emphasized. Analysis of the material focussed on the variation of the concentration of the shallow impurities for different V/III ratios. Surface and interface depletion effects are included to accurately estimate the concentration of impurities. The model of the merging of the excited states of the acceptor with the valence band is used to include the dependence the activation energy of the impurity on the acceptor concentration as well as on acceptor species identity. The characteristicp- ton-type conversion with increasing V/III ratio was observed in these samples and the reason for thep- ton-type conversion is that the background acceptor concentration of carbon decreases and the germanium donor concentration increases as the V/III ratio is increased.     

An Investigation of MIMO Performance in the Indoor Ricean Environment

In this paper, we investigate the Multiple-Input Multiple-Output (MIMO) channel capacity in indoor Ricean channels based on MIMO channel measurements at 2.45 GHz. The measured data is analysed using a super resolution parameter estimation algorithm. Our results demonstrate that the line-of-sight (LOS) component in a Ricean scenario influences indoor MIMO performance through increased spatial correlation between array elements. We found that indoor channels with higher values of Ricean K factor have smaller numbers of effective multipath components and increased spatial correlation. Measurement results also showed that, the effect of varying antenna height on indoor MIMO capacity is also due to the spatial correlation of multipath propagation and has a close relationship with the separation between the transmitter and receiver. Zhongwei Tang is currently with the Wireless Technologies Laboratory at CSIRO. He was with Microwave and Wireless Technology Research Laboratory (MWTRL), Information and Communication Group, Faculty of Engineering of the University of Technology Sydney, Australia, where he pursued his Ph.D. Degree. His current research interests include RF propagation, MIMO Space-Time channel measurements, characterization and channel modelling, smart antennas, MIMO systems and array signal processing. Ananda S. Mohan is currently a member of the Faculty of Engineering, University of Technology, Sydney (UTS), Australia where he leads research on antennas, microwaves, wave propagation, and wireless technology. He received a Ph.D. degree in electrical communication engineering from the Indian Institute of Technology, Kharagpur, India and was a Scientist and Senior Scientist at the Research and Training Unit for Navigational Electronics, Hyderabad, India. At UTS, he directed the Sydney microwave design resource centre and was the associate program leader of the co-operative research centre for satellite systems. He currently directs the microwave and wireless technology research laboratory and a core member of the university research centre on health technologies. His current teaching and research interests include wireless mobile communications, microwaves and antennas, smart antennas and applications of microwave and wireless technology in medicine and has obtained many competitive research grants in these areas. Dr. Mohan was a co-recipient of the Priestly memorial award from the Institute of Radio and Electronic Engineers (IREE), Australia. He was a member of the organizing and technical Program Committees of the IEEE Globecom'98, APMC 2000, and International Symposium on Wireless Systems and Networks, 2003 and IASTED International Conference on Antennas, Radar, and Wave Propagation, for 2004 and 2005.     

电离总剂量效应对HfO2栅介质经时击穿特性影响

针对纳米金属-氧化物-半导体(MOS)器件中采用的高介电常数Hf栅介质,开展电离总剂量效应对栅介质经时击穿特性影响的研究。以HfO₂栅介质MOS电容为研究对象,进行不同栅极偏置条件下⁶⁰Co-γ射线的电离总剂量辐照试验,对比辐照前后MOS电容的电流-电压、电容-电压以及经时击穿特性的测试结果。结果显示,不同的辐照偏置条件下,MOS电容的损伤特性不同。正偏辐照下,低栅压下的栅电流显著增大,电容电压特性的斜率降低;零偏辐照下,正向高栅压时栅电流和电容均显著增大;负偏辐照下,栅电流均有增大,正向高栅压下电容增大,且电容斜率降低。3种偏置下,电容的经时击穿电压均显著减小。该研究为纳米MOS器件在辐射环境下的长期可靠性研究提供了参考。     

A novel low-temperature method of SiO2 film deposition forMOSFET applications

Silicon dioxide dielectric films were deposited at low temperatures (250–300°) using a novel plasma enhanced MO-CVD process. In this process, the substrate was kept remote from the plasma region and the deposition of the film was achieved at low pressure (0.8-1.0 Torr) and low dc plasma power (0.3 W· cm⁻²). Films deposited using tetraethyloxysilane (TEOS) and nitrous oxide (N₂O) as reactant material had, under optimum deposition conditions, resistivities of ≥ 10¹⁵ ohm-cm, a refractive index of 1.46, a dielectric constant of 3.98 and a breakdown field strength ≥ 5x 10₆ V·cm⁻¹. AES and SIMS analysis indicated that the films were of high purity and were stoichiometric with no metallic silicon present. MOS-capacitors fabricated on Si-substrates showed no hysteresis and no frequency dispersion of capacitance in the accumulation region. An interface state density in the range of 10¹¹ cm⁻²eV⁻¹ was achieved for these MOS devices using our deposited SiO₂dielectric films.     

背向受激二波混频产生自泵浦相位共轭

本文讨论了在光折变晶体中,通过特殊的背向受激二波混频产生自泵浦相位共轭波的理论,并指出散射波的频偏是由于极化光折变晶体中的光生伏打效应引起相位栅的运动而产生的。     

Carrier transport and related phenomena in MOS devices

Silicon-based devices are currently the most attractive group because they are functioning at room temperature and can be easily integrated into conventional silicon microelectronics. There are many models and simulation programs available to compute CV curves with quantum correction [Choi C-H, Wu Y, Goo JS, Yu Z, Dutton RW. IEEE Trans on Electron Devi 2000; 47(10): 1843; Croci S, Plossu C, Burignat S. J Mater Sci Mater Electron 2003; 14: 311; Soliman L, Duval E, Benzohra M, Lheurette E, Ketata K, Ketata M. Mater Sci Semicond Process 2001; 4: 163]. This work deals with the simulation of electron transfer through SiO₂ barrier of metal–oxide–semiconductor structure (MOS). The carrier density is given by a self consistent resolution of Schrödinger and Poisson equations and then the MOS capacitance is deduced and compared with results available in literature. As it is well known, the MOS capacitance–voltage profiling provides a simple determination of structure parameters. The extracted tunnel oxide thickness and substrate doping are compared with those used in the simulation. For the purpose to investigate the electron tunnelling through the barrier, we have used the transfer matrix approach. Using I–V simulations, we have shown that the traps in SiO₂ matrix have a drastic influence on electron tunnelling through the barrier. The trap-assisted contribution to the tunnelling current is included in many models [Maserjian J, Zamani N. J Appl Phys 1982; 53(1): 559; Houssa M, Stesmans A, Heyns MM. Semicond Sci Technol 2001; 16: 427; Aziz A, Kassmi K, Kassmi Ka, Olivie F. Semicond Sci Technol 2004; 19: 877; Wu You-Lin, Lin Shi-Tin. IEEE Trans Dev Mater Reliab 2006; 6(1): 75; Larcher L. IEEE Trans Electron Dev 2003; 50(5): 1246]; this is the basis for the interpretation of stress induced leakage current (SILC) and breakdown events. Memory effect becomes typical for this structure. We have studied the I–V dependence with trap parameters.     

The meta-stable dip (MSD) effect in SOI FinFETs

The meta-stable dip (MSD) effect is demonstrated and characterized in SOI FinFETs. With ascending scan of front-gate voltage (V_G1), the magnitude of drain current (I_D) tends to be fixed within a specific region of the front-gate voltage and this leads to a dip of transconductance (g_m). The dip width can be modulated through a control of bias condition or measurement speed such as back-gate voltage (V_G2), drain voltage (V_D) and step size of the front-gate voltage. From the dual-gate transient measurement, it is found that the MSD effect is highly dependent on the floating-body effect. In SOI FinFETs, the MSD effect is significantly affected by the fin width due to the fringing electric field of the lateral gates.     

A Simulation-Based Proposed High-k Hetero Structure AlGaAs/Si Junction–Less N-Type Tunnel FET

We propose a heterostructure junctionless tunnel field effect transistor(HJL-TFET) using Al Ga As/Si.In the proposed HJL-TFET,low band gap silicon is used in the source side and higher band gap Al Ga As in the drain side.The whole Al Ga As/Si region is heavily doped n-type.The proposed HJL-TFET uses two isolated gates(named gate,gate1) with two different work functions(gate D4.2 e V,gate1D5.2 e V respectively).The 2-D nature of HJL-TFET current flow is studied.The proposed structure is simulated in Silvaco with different gate dielectric materials.This structure exhibits a high on current in the range of 1.4106A/ m,the off current remains as low as 9.11014A/ m.So I ON/I OFF ratio of’108is achieved.Point subthreshold swing has also been reduced to a value of’41 m V/decade for Ti O2 gate material.     

The negative differential resistance characteristics of an RC-IGBT and its equivalent circuit model

A simple equivalent circuit model is proposed according to the device structure of reverse conducting insulated gate bipolar transistors （RC-IGBT）. Mathematical derivation and circuit simulations indicate that this model can explain the snap-back effect （including primary snap-back effect, secondary snap-back effect, and reverse snap-back effect） and hysteresis effect perfectly.     

光学双稳系统的耗散与合作效应

本文基于作者所导出的混合型光学双稳系统与原子相关的耗散表达式,详细地讨论了光学双稳系统中原子间的相关效应,即合作效应。证明了在低透支上原子的合作行为,以及在高透支上的单原子行为,是—种普遍现象,不局限于理想化的二能级原子物质。     

无源谐振腔激光陀螺的背散射

从理论上证明了在闭环无源谐振腔激光陀螺中，谐振腔的腔镜背散射不但会引起闭锁效应，而且会引起模牵引效应。探讨了消除闭锁效应的根本方法。     

钛酸钡（BaTiO3）的光束Fanning效应

我们通过实验对激光束透过光折变晶体(BaTiO_3)产生的Fanning效应作了研究。晶体光轴取向、入射光束的偏振状态和入射角是影响光束Fanning效应的主要因素。本文给出实验结果并作了扼要的理论分析。     

Performance improvement mechanisms of organic thin-film transistors using MoOx-doped pentacene as channel layer

Organic thin-film transistors (OTFTs) with various MoO_x-doped pentacene channel layers were fabricated and investigated. Compared the OTFTs with the 0.50 mol% MoO_x-doped pentacene to the conventional OTFTs without MoO_x dopant, the maximum output current was increased from −11.6 to −37.9 μA, the effective field-effect mobility was enhanced from 0.71 to 1.60 cm²/V-s, the threshold voltage was reduced from −21.2 to −14.8 V, and the on/off current ratio slightly decreased from 3.6 × 10⁶ to 1.2 × 10⁶. The performance improvement was attributed to the highest occupied molecular orbital (HOMO) of the MoO_x-doped pentacene gradually approached to the Au work function with increasing the doping percentage of MoO_x, which led to reduce the contact resistance and to enhance the p-type characteristics of the MoO_x-doped OTFTs by increasing the hole density and enhancing the hole-injection efficiency. However, the output current and the field-effect mobility decreased with an increase of the MoO_x doping percentage, if the doping mole percentage of MoO_x was higher than 0.50%. This behavior was attributed to the Fermi level pinning effect, gradual increase of hole concentration and significant degradation of crystallinity.     

Recent Progress of Methods to Enhance Photovoltaic Effect for Self-Powered Heterojunction Photodetectors and Their Applications in Inorganic Low-Dimensional Structures

An important class of photoelectronic devices, self-powered photodetectors, has attracted worldwide attention because of its crucial role in both basic scientific research and commercial/public applications. Thanks to a special synergistic effect, excellent photoelectric properties, and outstanding mechanical stability, the study of heterojunction devices can provide valuable insights and new possibilities for the future of self-powered photodetectors. This paper reviews the recent years of fundamental research of photovoltaic efficiency based on the ferroelectric-enhanced photovoltaic effect, the pyro-phototronic effect, and the piezo-phototronic effect. It also highlights important topics related to heterojunctions and materials that are suitable for self-powered photodetectors. The article concludes with an outlook of the future development in this important and rapidly advancing field.     

Analytic approximation of the jitter incurred by CBR traffics in IP networks

In this paper, an analytic approximation is derived for the end-to-end delay-jitter incurred by a periodic traffic with constant packet size. The single node case is considered first. It is assumed that the periodic traffic is multiplexed with a background packet stream under the FCFS service discipline. The processes governing the packet arrivals and the packet sizes of the background traffic are assumed to be general renewal processes. A very simple analytical approximation is derived and its accuracy is assessed by means of event-driven simulations. This approximation is then extended to the multiple node case yielding a simple analytical approximation of the end-to-end jitter. This approximation is shown to be fairly accurate in the light to moderate traffic conditions typically encountered in IP core networks.