Optimization and modeling of ESD protection devices

“Transient voltage suppressors (TVS) are used to protect ICs (integrated circuits) against overvoltage, ESD (Electrostatic Discharge), inductive load switching, and even lightning strikes. In this research, a transient behavior model framework for ESD protection devices is used for modelling four different types of TVS (non-snapback, snapback, spark gap like device and varistor). The System-Efficient ESD Design (SEED) methodology is utilized to strengthen the trust in the model framework by efficient simulation of ESD interaction of the off-chip ESD protection devices with the IC ESD protection device and associated measurement data. Improvements in the TVS transient response, accounting for conductivity modulation, voltage overshot at the snapback voltage, etc., are required to accurately model the ESD protection device. With this in mind, the unimproved model is presented for various ESD protection device where their transient behavior of single component can be fully described by a quasistatic very fast transmission line pulse (VF)-TLP. The improved model is validated within a sub-system consisting of an off-chip ESD protection device, an IC on-chip protection and a PCB trace in between. Multiple solutions to avoid convergence issues are also proposed for effective simulation”--Abstract, page iv

Epitaxial designs for maximizing efficiency in resonant tunnelling diode based terahertz emitters

We discuss the modelling of high current density InGaAs/AlAs/InP resonant tunneling diodes to maximize their efficiency as THz emitters. A figure of merit which contributes to the wall plug efficiency, the intrinsic resonator efficiency, is used for the development of epitaxial designs. With the contribution of key parameters identified, we analyze the limitations of accumulated stress to assess the manufacturability of such designs. Optimal epitaxial designs are revealed, utilizing thin barriers, with a wide and shallow quantum well that satisfies the strained layer epitaxy constraint. We then assess the advantages to epitaxial perfection and electrical characteristics provided by devices with a narrow InAs sub-well inside a lattice-matched InGaAs alloy. These new structures will assist in the realization of the next-generation submillimeter emitters

TVS transient behavior modeling method, and system-level effective ESD design for USB3.x interface

This research proposal presents a methodology whereby a protection device can be modeled in SPICE compatible platforms with respect to the transient behaviors during Electrostatic Discharge (ESD) events. This methodology uses an exclusively black-box approach to characterize the parameters of the protection device, thereby allowing it to be implemented without intimate knowledge of the DUT. Results of this methodology can be used to predict the transient response (conductivity modulation and snapback delay) of the ESD protection devices, and thereby predicts how much current could flow into the device (typically a digital IO pin) under protection. The transient behavior modeling methodology for the ESD protection device is developed for the purpose of system level ESD design, and it is part of the study of System-level Effective ESD Design (SEED) methodology. During the work, the transient behavior modeling method and the SEED methodology have been applied to a high-speed USB3.x repeater IC circuit design. This article introduces a PCB test board working as USB3.x repeater, which allows to place various on-board protection devices and to measure the residual voltage and current at the IO pin accurately. In Section 2, the transient behavior modeling framework and the characterization method will be introduced. The validation results of three different types of protection devices are shown in the end of the section. In Section 3, the implementation of SEED methodology to a USB3.x system design will be introduced. The measurement setup is described in detail. Finally, the validation results for different scenarios will be shown --Abstract, page iii

Nonlinear Control of Tunneling Through an Epsilon-Near-Zero Channel

The epsilon-near-zero (ENZ) tunneling phenomenon allows full transmission of waves through a narrow channel even in the presence of a strong geometric mismatch. Here we experimentally demonstrate nonlinear control of the ENZ tunneling by an external field, as well as self-modulation of the transmission resonance due to the incident wave. Using a waveguide section near cut-off frequency as the ENZ system, we introduce a diode with tunable and nonlinear capacitance to demonstrate both of these effects. Our results confirm earlier theoretical ideas on using an ENZ channel for dielectric sensing, and their potential applications for tunable slow-light structures

Characterization and modeling of ESD events, risk and protection

“The ESD (Electrostatic discharge) failures have been raising critical reliability problems in electronic devices design. However, not all the ESD scenarios have been specified by the IEC standard and the characterizations of the ESD risk for different scenarios are essential to evaluate the ESD robustness of the devices in the real word. The insulation of plastic enclosures provides protection against ESD to the electronic system inside. However, seams between plastic parts are often unavoidable. Different plastic arrangements are constructed to investigate the spark length and current derivatives and to understand the ESD spark behavior for geometries having spark lengths longer than the values predicted by Paschen’s law. For the wearable devices, the core difference between the posture assumed for IEC 61000-4-2 human metal discharge and a discharge to a wearable device is the impedance between the charged body and the grounded structure discharged to. The results show that the current measured in the brush-by scenario can reach values twice as high as the current specified in the IEC standard. A simulation model using the measured impedance and Rompe and Weizel’s law provides predictions on the peak current derivative when the spark length is varied. The increasing peak current derivative with shorter spark length indicates stronger field coupling to the devices. SEED(System-efficient ESD design) modeling helps the designer to predict the ESD risk at the early stage, an accurate TVS model can be used to study the transient response of the external TVS and the on-chip protection when applied in a typical high-speed input/output (I/O) interface”--Abstract, page iv

System efficient ESD design concept for soft failures

This research covers the topic of developing a systematic methodology of studying electrostatic discharge (ESD)-induced soft failures. ESD-induced soft failures (SF) are non-destructive disruptions of the functionality of an electronic system. The soft failure robustness of a USB3 Gen 1 interface is investigated, modeled, and improved. The injection is performed directly using transmission line pulser (TLP) with varying: pulse width, amplitude, polarity. Characterization provides data for failure thresholds and a SPICE circuit model that describes the transient voltage and current at the victim. Using the injected current, the likelihood of a SF is predicted. ESD protection by transient voltage suppressor (TVS) diodes is numerically simulated in several configurations. The results strongly suggest the viability of using well-established hard failure mitigation techniques for improving SF robustness, and the possibility of using numerical simulation for optimization purposes. A concept of soft failure system efficient ESD design (SF-SEED) is proposed and shown to be effective --Abstract, page iv

A Study on SPICE Modeling of Non-Resonant Plasmonic Terahertz Detector

Department Of Electrical EngineeringThe terahertz (sub-millimeter wave) is the frequency resource, ranging from 100 GHz ~ 10 THz band, located in the middle region of the infrared and millimeter waves in the electromagnetic spectrum. Terahertz waves has unique physical characteristics, which is transparency of radio waves and straightness of light waves, simultaneously. The terahertz wave is applied to the basic science, such as device, spectroscopy, and imaging technology. And also adjust in the applied science, such as biomedical engineering, security, environment, information and communication. Which importance already verified. In the new shape of future market is expected to be formed broadly. For this application, operating in the THz frequency detecting device essential. Recently, Current elements operating in terahertz are present, such as compound semiconductor (???-???HBT, HEMT). But, there are disadvantage to use as a high price. Therefore, research have been made of silicon based THz detector in many research groups. Silicon-based nano-technology utilizes a plasma wave transistor technology. Which is using the space-time change of the channel charge density. That causes plasma wave oscillation in the MOSFET (Metal oxide semiconductor field effect transistor) channel and this effect available MOSET operating terahertz regime beyond MOSFET cut-off frequency. So, PWT (plasma wave transistor) is available terahertz detection and oscillation. For integrated possible post processing circuit development in these of terahertz applications system, silicon based PWT compact model is essential thing. For this compact model for spice simulation beyond cut-off frequency, we consider charge time variance model which is NQS (non-quasi-static) model, not quasi-static model. For NQS model two kinds of model exist, first is RC ladder model. That is seral connect MOSFET get rid of parasitic elements. And these complex circuit making the equivalent circuit model, it called New Elmore model. For post processing circuit simulation, fast simulation speed is essential, RC ladder model has a disadvantage (for simulating each segment). In this thesis we using New Elmore model based on Non-resonant plasmonic THz detector modeling, And verified physical validity of our NQS model using the our TCAD model based on Quasi-plasma 2DEG. And we propose fast and accurate compact modelingope

Asymptotic solution of a model for bilayer organic diodes and solar cells

The current voltage characteristics of an organic semiconductor diode made by placing together two materials with dissimilar electron affinities and ionisation potentials is analysed using asymptotic methods. An intricate boundary layer structure is examined. We find that there are three regimes for the total current passing through the diode. For reverse bias and moderate forward bias the dependency of the voltage on the current is similar to the behaviour of conventional inorganic semiconductor diodes predicted by the Shockley equation and are governed by recombination at the interface of the materials. There is then a narrow range of currents where the behaviour undergoes a transition. Finally for large forward bias the behaviour is different with the current being linear in voltage and is primarily controlled by drift of charges in the organic layers. The size of the interfacial recombination rate is critical in determining the small range of current where there is rapid transition between the two main regimes. The extension of the theory to organic solar cells is discussed and the analogous current voltage curves derived in the regime of interest