A novel diode string triggered gated-Pi N junction device for electrostatic discharge protection in 65-nm CMOS technology

A novel diode string-triggered gated-Pi N junction device, which is fabricated in a standard 65-nm complementary metal-oxide semiconductor(CMOS) technology, is proposed in this paper. An embedded gated-Pi N junction structure is employed to reduce the diode string leakage current to 13 n A/μm in a temperature range from 25°C to 85°C. To provide the effective electrostatic discharge(ESD) protection in multi-voltage power supply, the triggering voltage of the novel device can be adjusted through redistributing parasitic resistance instead of changing the stacked diode number.     

Novel substrate trigger SCR-LDMOS stacking structure for high-voltage ESD protection application

A novel substrate trigger semiconductor control rectifier-laterally diffused metal–oxide semiconductor(STSCRLDMOS) stacked structure is proposed and simulated using the transimission line pulser(TLP) multiple-pulse simulation method in a 0.35-μm, 60-V biploar-CMOS-DMOS(BCD) process without additional masks. On account of a very low holding voltage, it is susceptible to latch-up-like danger for the semiconductor control rectifier-laterally diffused metal–oxide semiconductor(SCR-LDMOS) in high-voltage electro-static discharge(ESD) protection applications. Although the conventional stacking structure has achieved strong latch-up immunity by increasing holding voltage, excessive high trigger voltage does not meet requirements for an ESD protection device. The holding voltage of the proposed stacked structure is proportional to the stacking number, whereas the trigger voltage remains nearly the same. A high holding voltage of 30.6 V and trigger voltage of 75.4 V are achieved.     

New DDSCR structure with high holding voltage for robust ESD applications

A novel dual direction silicon-controlled rectifier(DDSCR)with an additional P-type doping and gate(APGDDSCR)is proposed and demonstrated.Compared with the conventional low-voltage trigger DDSCR(LVTDDSCR)that has positive and negative holding voltages of 13.371 V and 14.038 V,respectively,the new DDSCR has high positive and negative holding voltages of 18.781 V and 18.912 V in a single finger device,respectively,and it exhibits suitable enough positive and negative holding voltages of 14.60 V and 14.319 V in a four-finger device for±12-V application.The failure current of APGDDSCR is almost the same as that of LVT-DDSCR in the single finger device,and the four-finger APGDDSCR can achieve positive and negative human-body model(HBM)protection capabilities of 22.281 kV and 23.45 kV,respectively,under 40-V voltage of core circuit failure,benefitting from the additional structure.The new structure can generate a snapback voltage on gate A to increase the current gain of the parasitic PNP in holding voltage.Thus,a sufficiently high holding voltage increased by the structure can ensure that a multi-finger device can also reach a sufficient holding voltage,it is equivalent to solving the non-uniform triggering problem of multi-finger device.The operating mechanism and the gate voltage are both discussed and verified in two-dimensional(2D)simulation and experiemnt.     

A novel four-legged loaded element thick-screen frequency selective surface with a stable performance

<正>A thick-screen frequency selective surface(FSS) has not only a broad bandwidth but also the advantages of overcoming the multilayer FSS shortcoming of complex structure and low transmittance of centre frequency due to the cascade of FSSs,and this means it could potentially be applied in a stealth curved streamlined radome.However,there is an unsteadiness of centre frequency in a wide range of incident angles and another unsteadiness of polarization in a big incident angle.In order to solve these problems,in this paper we provide a novel four-legged loaded element thick-screen FSS.The structure is analysed and simulated using the mode matching method and moment method.The centre frequency,the transmittance of centre frequency,and bandwidth of the structure are investigated when some parameters including the polarization at a big incident angle and the incident angles of TE & TM waves are changed. The novel four-legged loaded element thick-screen FSS has better transmission properties with a better steadiness of polarization and incident angle independence.The novel structure of the four-legged loaded element thick-screen FSS provides a valuable reference for their application in a stealth curved streamlined radome.     

High holding voltage SCR for robust electrostatic discharge protection

A novel silicon controlled rectifier(SCR) with high holding voltage(Vh) for electrostatic discharge(ESD) protection is proposed and investigated in this paper. The proposed SCR obtains high Vhby adding a long N+ layer(LN+) and a long P+ layer(LP+), which divide the conventional low voltage trigger silicon controlled rectifier(LVTSCR) into two SCRs(SCR1: P+/Nwell/Pwell/N+ and SCR2: P+/LN+/LP+/N+) with a shared emitter. Under the low ESD current(IESD), the two SCRs are turned on at the same time to induce the first snapback with high V_h(V_(h1)). As the IESDincreases, the SCR2 will be turned off because of its low current gain. Therefore, the IESDwill flow through the longer SCR1 path, bypassing SCR2, which induces the second snapback with high V_h(V_(h2)). The anti-latch-up ability of the proposed SCR for ESD protection is proved by a dynamic TLP-like(Transmission Line Pulse-like) simulation. An optimized V_(h2) of 7.4 V with a maximum failure current(I_(t2)) of 14.7 m A/μm is obtained by the simulation.     

Multilayer-core fiber with a large mode area and a low bending loss

We present a single-mode multilayer-core fiber with a large mode area(LMA) and a low bending loss in this Letter. A low equivalent core-cladding refractive index difference is achieved by exploiting the multilayer structure. The multilayer structure has a better bending performance than a traditional step-index core and this structure also contributes to realizing different curved refractive index profiles that have a better bending performance. An index trench is also introduced to dramatically reduce the bending loss. The experimental results show that, at a wavelength of 1550 nm, the mode area of the fabricated fiber is about 215.5 μm~2 and the bending loss is 0.58 dB/turn at a 10 mm bending radius. The LMA and excellent bending performance can be obtained simultaneously with the proposed fiber.     

Growth of a Novel Periodic Structure of SiC/AIN Multilayers by Low Pressure Chemical Vapour Deposition

A novel lO-period SiC/A1N multilayered structure with a SiC cap layer is prepared by low pressure chemical vapour deposition （LPCVD）. The structure with total film thickness of about 1.45~m is deposited on a Si （111） substrate and shows good surface morphology with a smaller rms surface roughness of f.3 nm. According to the secondary ion mass spectroscopy results, good interface of the 10 period SiC/A1N structure and periodic changes of depth profiles of C, Si, A1, N components are obtained by controlling the growth procedure. The structure exhibits the peak reflectivity close to 30% near the wavelength of 322 nm. To the best of our knowledge, this is the first report of growth of the SiC/AIN periodic structure using the home-made LPCVD system.     

A novel slotted helix slow-wave structure for high power Ka-band traveling-wave tubes

A novel slotted helix slow-wave structure （SWS） is proposed to develop a high power, wide-bandwidth, and high reliability millimeter-wave traveling-wave tube （TWT）. This novel structure, which has higher heat capacity than a conven- tional helix SWS, evolves from conventional helix SWS with three parallel rows of rectangular slots made in the outside of the helix tape. In this paper, the electromagnetic characteristics and the beam-wave interaction of this novel structure operating in the Ka-band are investigated. From our calculations, when the designed beam voltage and beam current are set to be 18.45 kV and 0.2 A, respectively, this novel circuit can produce over 700-W average output power in a frequency range from 27.5 GHz to 32.5 GHz, and the corresponding conversion efficiency values vary from 19% to 21.3%, and the maximum output power is 787 W at 30 GHz.     

A Quasi-Symmetric Coupled Quantum Well and Its Electric-Optical Properties

We propose a novel coupled quantum well structure, i.e. a quasi-symmetric coupled quantum well (QSCQW). Based on the demands of optical switching devices for quantum well materials, the QSCQW configuration is further optimized. Consequently, in the case of low applied electric field 25kV/cm and low absorption loss 100cm^-1, a large field-induced refractive index change (for TE mode, n = 0.0106; for TM mode, n = 0.0115) is obtained in the QSCQW structure at the operation wavelength 1550hm. The value is in one or two order of magnitude larger than that in a rectangular quantum well and about 50% larger than that of five-step asymmetric coupled quantum well structure under the same working conditions. The refractive index change obtained with the optimized QSCQW under so low absorption loss and applied electric field is very attractive for semiconductor optical switching devices. This manifests that the QSCQW structure has a great potential for applications in ultra-fast and low-voltage optical switches and in travelling wave modulators.     

3-D flame temperature field reconstruction with multiobjective neural network

A novel 3-D temperature field reconstruction method is proposed in this paper, which is based on multi-wavelength thermometry and Hopfield neural network computed tomography. A mathematical model of multi-wavelength thermometry is founded, and a neural network algorithm based on multiobjective optimization is developed. Through computer simulation and comparison with the algebraic reconstruction technique (ART) and the filter back-projection algorithm (FBP), the reconstruction result of the new method is discussed in detail. The study shows that the new method always gives the best reconstruction results. At last, temperature distribution of a section of four peaks candle flame is reconstructed with this novel method.     

Inner Structure of Boiling Nucleus and Interfacial Energy Between Nucleus and Bulk Liquid

A model of two-region structure of a nucleus is proposed to describe nucleus evolution.The interracial tension between bulk liquid phase and nucleus is dependent on the density gradient in the transition region and varies with the structure change of the transition region.With the interracial tension calculated using this model,the predicted nucleation rate is very close to the experimental measurement.Furthermore,this model and associated analysis provide solid theoretical evidence to clarify the definition of nucleation rate and understand the nucleation phenomenon with insight into the physical nature.     

A novel coupled quantum well structure with large field-induced refractive index change and low absorption loss at 1.55 μm

A novel coupled quantum well structure - quasi-symmetric coupled quantum well (QSCQW) is proposed.In the case of low applied electric field (F = 25 kV/cm) and low absorption loss (α≈ 100 cm-1), a large field-induced refractive index change (for TE mode, △n = 0.0106; for TM mode, △n ＝ 0.0115) is obtained in QSCQW structure at operating wavelength λ =1550 nm. The value is larger by over one to two order of magnitude compared to that in a rectangular quantum well (RQW) and about 50% larger than that of five-step asymmetric coupled quantum well (FACQW) structure under the above work conditions.     

GaN Films Grown on Si （111） Substrates Using a Composite Buffer with Low Temperature A1N Interlayer

A GaN interlayer between low temperature （LT） A1N and high temperature （PIT） A1N is introduced to combine HT AIN, LT A1N and composition-graded A1GaN as a novel buffer layer for GaN films grown on Si （111） substrates. The crystal quality, surface morphology and strain state of the GaN film with this new buffer are compared with those of GaN grown on a conventional buffer structure. By changing the thickness of LT A1N, the crystal quality is optimized and the crack-free GaN film is obtained. The in-plane strain in the GaN film can be changed from tensile to compressive strain with the increase in LT A1N thickness.     

HEM11 mode magnetically insulated transmission line oscillator： Simulation and experiment

A novel magnetically insulated transmission line oscillator （MILO） in which a modified HEM11 mode is taken as its main interaction mode （HEM11 mode MILO） is simulated and experimented in this paper. The excitation of the oscillation mode is made possible by carefully adjusting the arrangement of each resonant cavity in a two-dimensional slow wave structure. The special feature of such a device is that in the slow-wave-structure region, the interaction mode is HEM11 mode which is a TM-like one that could interact with electron beams effectively; and in the coaxial output region, the microwave mode is TE11 mode which has a favourable field density pattern to be directly radiated. Employing an electron beam of about 441 kV and 39.7 kA, the HEM11 mode MILO generates a high power microwave output of about 1.47 GW at 1.45 GHz in particle-in-cell simulation. The power conversion efficiency is about 8.4 % and the generated microwave is in a TEll-like circular polarization mode. In a preliminary experiment investigation, high power microwave is detected from the device with a frequency of 1.46 GHz, an output energy of 43 J 47 J, and a pulse duration of 44 ns-49 ns when the input voltage is 430 kV450 kV, and the diode current is 37 kA-39 kA.     

Design principles of a novel X-ray imaging system

A novel X-ray imaging system (NXRIS) and the design principles are given in this paper. Different from the existing digital X-ray imaging systems, the X-ray image intensifying system of NXRIS is a non-vacuum system composed of the intensifying screen and the brightness intensifier, and the brightness intensifier is named low light level image intensifier applied in military affairs. This structure makes NXRIS of big visual field (15 inch, even to larger) and low cost. When designing NXRIS, the spectral compatibility of the component devices and the relation between the visual field and the spatial resolution of the component devices are analyzed. The images produced by NXRIS are given and the image performance is good enough to be applied to security checking, non-destructive testing, and industry detection.     

HEM₁₁ mode magnetically insulated transmission line oscillator:Simulation and experiment

A novel magnetically insulated transmission line oscillator(MILO) in which a modified HEM 11 mode is taken as its main interaction mode(HEM 11 mode MILO) is simulated and experimented in this paper.The excitation of the oscillation mode is made possible by carefully adjusting the arrangement of each resonant cavity in a two-dimensional slow wave structure.The special feature of such a device is that in the slow-wave-structure region,the interaction mode is HEM 11 mode which is a TM-like one that could interact with electron beams effectively;and in the coaxial output region,the microwave mode is TE 11 mode which has a favourable field density pattern to be directly radiated.Employing an electron beam of about 441 kV and 39.7 kA,the HEM 11 mode MILO generates a high power microwave output of about 1.47 GW at 1.45 GHz in particle-in-cell simulation.The power conversion efficiency is about 8.4 % and the generated microwave is in a TE 11-like circular polarization mode.In a preliminary experiment investigation,high power microwave is detected from the device with a frequency of 1.46 GHz,an output energy of 43 J-47 J,and a pulse duration of 44 ns-49 ns when the input voltage is 430 kV-450 kV,and the diode current is 37 kA-39 kA.     

Structure-dependent behaviors of diode-triggered silicon controlled rectifier under electrostatic discharge stress

The comprehensive understanding of the structure-dependent electrostatic discharge behaviors in a conventional diode-triggered silicon controlled rectifier(DTSCR) is presented in this paper. Combined with the device simulation, a mathematical model is built to get a more in-depth insight into this phenomenon. The theoretical studies are verified by the transmission-line-pulsing(TLP) test results of the modified DTSCR structure, which is realized in a 65-nm complementary metal–oxide–semiconductor(CMOS) process. The detailed analysis of the physical mechanism is used to provide predictions as the DTSCR-based protection scheme is required. In addition, a method is also presented to achieve the tradeoff between the leakage and trigger voltage in DTSCR.     

Fluid Dynamics (Science Press, Beijing, 2004).Design principles of a novel X-ray imaging system

A novel X-ray imaging system (NXRIS) and the design principles are given in this paper. Different from the existing digital X-ray imaging systems, the X-ray image intensifying system of NXRIS is a non-vacuum system composed of the intensifying screen and the brightness intensifier, and the brightness intensifier is named low light level image intensifier applied in military affairs. This structure makes NXRIS of big visual field (15 inch, even to larger) and low cost. When designing NXRIS, the spectral compatibility of the component devices and the relation between the visual field and the spatial resolution of the component devices are analyzed. The images produced by NXRIS are given and the image performance is good enough to be applied to security checking, non-destructive testing, and industry detection.     

The principle of the Internet evolving and the conjecture of the optimal structure of Internet

In this paper we will give the statistical characteristics and general principles of an optimal structure of the Internet, which is a scale-free network. Since the purpose of the Internet is to allow fast and easy communication, the average path length is used to measure the performance of the network, and the number of edges of the network is used as a metric of its cost. Based on this, the goal of this Internet optimization problem is to obtain the highest performance with the lowest cost. A multi goal optimization problem is proposed to model this problem. By using two empirical formulas of and , we are able to find the statistical characteristics of the optimal structure. There is a critical power law exponent α _c for the Internet with power law degree distribution, at which the Internet can obtain a relatively good performance with a low cost. We find that this α _c is approximately 2.1.     

Study of a compact external magnetic field radial split-cavity oscillator

With the experiment result analyses of a coaxial virtual cathode oscillator (CVCO), a new kind of compact radial split cavity oscillator (RSCO) is presented in this paper. On the oscillator, a low resistance tube is formed by using the diode structure of a CVCO, and a radial split-cavity structure is formed by several meshes that cause the electronic beam to transmit. Calculating all kinds of parameter, at the input parameter 350 kV, 27 kA, the numerical simulation results show that the average output microwave power is about 4.0 GW, the microwave frequency is 1.37 GHz, and the electronic efficiency is 42.3%.