Silicon MOSFETs Research Articles

A Highly Scalable, Modular Test Bench Architecture for Large-Scale DC Power Cycling of SiC MOSFETs: Towards Data Enabled Reliability

Silicon carbide (SiC) power MOSFETs have superior conduction, switching and thermal properties compared to silicon (Si) MOSFETs and IGBTs [1]. However, unlike Si devices, whose reliability is well understood from decades of research and field data, SiC device technology is relatively nascent and has only recently started witnessing wide scale deployment. This reliability challenge can possibly be addressed through two complementary solutions as shown in Figure 1: 1) developing a large accelerated aging dataset of SiC devices under various conditions to understand their long term reliability and guide future device development, 2) using on-board, in-system prognostics and device health monitoring techniques to predict imminent device failures well ahead of time, thus ensuring reliable system operation [2]. In both cases, the large-scale reliability testing of SiC MOSFETs is needed. Generally, remaining useful lifetime (RUL) estimation methods for power devices use an empirical model obtained from fitting accelerated aging data [3]-[7], [9], [10]. Consequently, the accuracy of RUL models is directly related to the size and variety of available accelerated aging dataset. Moreover, large datasets are crucial in enabling machine learning (ML) and artificial intelligence (AI) based reliability models.

Evaluation of silicon MOSFETs and GaN HEMTs in soft‐switched and hard‐switched DC‐DC boost converters for domestic PV applications

Hard‐switched high‐gain DC‐DC converters such as the boost converter play an important role in renewable energy systems. Research to increase their efficiency is important and can be achieved using soft‐switching techniques; however, that approach requires an auxiliary circuit. The auxiliary circuit decreases power density and reliability while increasing the cost. Moreover, soft‐switching topologies usually cannot improve the efficiency for all power and voltage ranges. Wide bandgap (WBG) devices, such as gallium nitride (GaN), result in lower switching losses than silicon (Si), can be used while retaining the simple structure of a hard‐switched topology. However, the high cost of these devices is problematic for their frequently cost‐sensitive applications. To quantify the cost and efficiency, this study compares soft‐switching techniques and WBG‐based switches in DC‐DC boost converters for a photovoltaic (PV) energy application. The performance of four prototypes including the soft‐switched and hard‐switched DC‐DC converters with both state‐of‐the‐art Si and GaN switches are evaluated in terms of cost, power density, efficiency, and reliability using theoretical analysis, simulation and experimental results. It is shown that the GaN‐based hard‐switched converter provides higher efficiency and power density; it is more expensive than its Si‐based counterpart, yet is cheaper than soft‐switched converters.

The Study of the Single Event Effect in AlGaN/GaN HEMT Based on a Cascode Structure

An attractive candidate for space and aeronautic applications is the high-power and miniaturizing electric propulsion technology device, the gallium nitride high electron mobility transistor (GaN HEMT), which is representative of wide bandgap power electronic devices. The cascode AlGaN/GaN HEMT is a common structure typically composed of a high-voltage depletion-mode AlGaN/GaN HEMT and low-voltage enhancement-mode silicon (Si) MOSFET connected by a cascode structure to realize its enhancement mode. It is well known that low-voltage Si MOSFET is insensitive to single event burnout (SEB). Therefore, this paper mainly focuses on the single event effects of the cascode AlGaN/GaN HEMT using technical computer-aided design (TCAD) simulation and heavy-ion experiments. The influences of heavy-ion energy, track length, and track position on the single event effects for the depletion-mode AlGaN/GaN HEMT were studied using TCAD simulation. The results showed that a leakage channel between the gate electrode and drain electrode in depletion-mode AlGaN/GaN HEMT was formed after heavy-ion striking. The enhancement of the ionization mechanism at the edge of the gate might be an important factor for the leakage channel. To further study the SEB effect in AlGaN/GaN HEMT, the heavy-ion test of a cascode AlGaN/GaN HEMT was carried out. SEB was observed in the heavy-ion irradiation experiment and the leakage channel was found between the gate and drain region in the depletion-mode AlGaN/GaN HEMT. The heavy-ion irradiation experimental results proved reasonable for the SEB simulation for AlGaN/GaN HEMT with a cascode structure.

Particularities of the Short-Circuit Operation and Failure Modes of SiC-MOSFETs

During short-circuit operation, silicon carbide MOSFETs exhibit several peculiarities compared to conventional silicon MOSFETs. These comprise the influence of the <bold xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</b> -state gate–source voltage on the short-circuit (SC) current, the emergence of high gate leakage currents, and finally special failure types, such as the gate breakdown and the delayed thermal runaway. We investigate all those particularities but pay special attention to the impact and composition of the drain leakage current and the breakdown of the gate insulation. We use special measurement techniques to determine the threshold voltage and transfer characteristics at temperatures close to those during an SC event. Under these conditions, the threshold voltage can become negative. Thus, in addition to thermally generated carriers and the parasitic BJT, the channel can also contribute to the drain leakage current. To investigate the gate failure, we apply repetitive stress in different operating points. The results comply with Weibull and Coffin–Manson models, which indicates that the underlying defect mechanism is of thermomechanical nature.

Silicon Carbide Multi-Chip Power Module for Traction Inverter Applications: Thermal Characterization and Modeling

Semiconductor power modules are the key hardware components of a traction inverter. It drives motor speed and torque, managing the energy exchange from battery to motor and viceversa. The increasing demand for electric and hybrid vehicle requests high performance power modules. Power semiconductor devices based on wide band gap compound, like silicon carbide (SiC), have excellent electrical properties in terms of on-state resistance, stray inductance and performance at high commutation frequency. One of the most promising solution is silicon carbide MOSFET power module in which each switch is made by several different dies placed in parallel. Embedded direct cooling system and novel materials with high conductivity (e.g., active metal brazed substrates) can be considered to enhance thermal performance. A robust method is needed to characterize and to predict power module temperature behavior considering the importance of the thermal performance to improve reliability and to optimize module weight and dimensions. According to several parallel dies inside each switch, classic method based on temperature electric sensitive parameter (TSEP) shall be validated with direct measurement. In this framework, it has been reported the thermal characterization of a power module for a traction inverter based on eight silicon carbide MOSFETs for each switch. Both TSEP and infrared measurements have been employed. Thermal behavior has been numerically reproduced, creating a simplified equivalent network and developing a predictive model by finite element method (FEM).

Silicon made switches for the development of low cost asymmetric 25 level inverter

This paper proposes the development of 25 level asymmetric inverter using four sources and ten switches. The proposed system consists of four sources which are asymmetrical in nature. Different structures of MLI were developed by researches to decrease the switch count and cost. The design of T-type inverter made using silicon MOSFET fed with asymmetric voltage source. In this topology staircase output voltage of twenty-five level is generated with minimum components count. The designed topology can be used for renewable energy sources to obtain inverted output.

High-Frequency Wide-Range Resonant Converter Operating as an Automotive LED Driver

This article introduces an immittance network-based wide-range LCL-T resonant dc–dc converter, where two control variables, a phase shift between two inverter half-bridges, and a phase shift between inverter and rectifier half-bridges, are utilized to achieve output current regulation while minimizing losses over wide ranges of input and output voltages. A practical control strategy is developed to adjust the phase shifts so that zero voltage switching of all devices is achieved while minimizing conduction losses. Efficiency improvements over a standard LCL-T converter are demonstrated by loss modeling and by experiments. The features of the proposed WR-LCL-T converter are well suited for automotive LED drivers. Experimental results demonstrating operation with the loss minimizing control strategy are shown for a 2-MHz converter prototype operating from an input voltage ranging from 8 to 18 V, and delivering 0.5-A output current to a string of 1–14 LEDs, which corresponds to an output voltage range of 3–45 V. Using silicon MOSFETs, the prototype achieves a peak power stage efficiency of 92.4% and maintains greater than 86% power stage efficiency across the wide input and output voltage ranges.

Analysis of Potential and Electron Density Behaviour in Extremely Scaled Si and InGaAs MOSFETs Applying Monte Carlo Simulations

Scaling of Silicon and InGaAs MOSFETs of a 25 nm gate length till shortest gate length of 5 nm, simulated this nano-device by Monte Carlo (MC) with quantum corrections. The transistors are scaled-down only in lateral dimensions in order to study electron transport approaching a ballistic limit along the scaled channel following experimental works. These MC simulations are able to give detailed insight into physical behaviour of electron velocity, electron density, and potential in relation to the drive current. We found that electron peak velocity increases during the scaling in Si MOSFETs till the 10 nm gate length and then dramatically declines due to a strong long-range Coulomb interaction among the source and the drain [16]. This effect is not observed in the equivalent InGaAs MOSFETs in which electron peak velocity exhibits double peak which steadily increases during the scaling [16]. However, the increasing of current in the equivalent InGaAs MOSFETs is moderate, by about 24 %, by comparing of current in the Si MOSFETs of 74 % delivered by 5 nm channel transistor.

Static model of power silicon MOSFET.

Static model of power silicon MOSFET.

New Insight into Single-Event Radiation Failure Mechanisms in Silicon Carbide Power Schottky Diodes and MOSFETs

Ion-induced leakage current degradation, and single-event burnout may be manifestestations of the same device mechanisms in both silicon carbide power diodes and MOSFETs. In all cases there is a migration of the electrical field from the front body-drain interface to the back epi-drain n+ interface, with a peak exceeding the critical electric field of silicon carbide, causing avalanche generation which enables high short-duration power densities during an approximate 20 psec window after the ion strike. The degradation effect in JBS SiC diodes seems to be independent of the length of the epitaxial region for different voltage-rated diodes.

Effect of Latitudinal and Longitudinal Grain Boundaries on the Characteristics of Polycrystalline Silicon MOSFET Devices

The MOSFETs, Complementary MOS-ICs are the core switch devices of current which also critically affects the ICs. For higher IC performance the present era has shifted to the device scaling to sub-50nm range TFT (thin film transistor) based MOSFET which involves complex fabrication process. The presence of grain boundaries greatly affects the characteristics of these devices. Present paper describes dependence of output characteristics inpolycrystalline silicon MOSFET devices on the longitudinal and latitudinal grain boundaries (GBs) have been investigated theoretically. It is observed that in both latitudinal and longitudinal GBs, the GB scattering potential ‘qφ’ and the GB distribution parameter ‘s’ are equally involved. At all values of gate voltages the contribution in drain current of the device is more due to latitudinal GBs in comparison to longitudinal GBs. However, at high gate voltages longitudinal GBs play a significant role in the drain current of the device.The theoretical computations of the model are synonymous to the experimental work.

Online Detection of MOSFET Gate Oxide Degradation in a Three-Phase Inverter-Drive Application

Failure in electrical machines or their drives can be catastrophic in safety-critical applications. Both silicon and silicon-carbide MOSFETs experience gate oxide degradation that leads to device failure. It is ideal to detect gate oxide degradation early using noninvasive, online techniques. In this article, an online gate oxide degradation detection method is proposed to reduce the reliability concern of using MOSFET switching devices. Gate oxide degradation causes a delay in phase current rise. Although the delay is short, it affects the voltage commands calculated in the controller. It is shown through analysis, simulation, and experiment that space vector pulsewidth modulation (SVPWM) duty cycle commands reflect the delay in phase current rise caused by gate oxide degradation.

Performance of SiC cascode JFETs under single and repetitive avalanche pulses

In this paper, we investigate the single and repetitive avalanche performance and characteristics of different SiC device technologies including SiC cascode JFETs and SiC Trench MOSFETs. SiC Cascode JFETs exhibit a different failure mode from SiC MOSFETs due to the interaction between the low-voltage (LV) silicon MOSFET and the high-voltage (HV) SiC JFET through the resistance connecting the MOSFET source to the JFET gate. MOSFETs fail in avalanche typically due to parasitic BJT latch-up and/or thermal hot-spotting leading to a source-to-drain short. However, cascode JFETs can fail with the low voltage MOSFET still functional and a low resistance measured between the cascode terminals. The failure point of SiC Cascode JFETs in avalanche is therefore not clearly identifiable and the failure criteria will have to be reassessed. Measurements and simulations show that the connection between the JFET gate and the MOSFET source influences the avalanche duration and avalanche power. Finite element simulations show that increased leakage through the gate resistance of the SiC JFET at higher temperatures causes delayed transients in the VDS turn-OFF. Hence, the result is low-voltage avalanche turn-OFF where only the LV silicon MOSFET goes into avalanche and the JFET goes into linear mode. SiC Cascode JFETs show reduced performance under repetitive avalanche due to degradation of the JFET gate resistance and increased linear mode conduction of the SiC JFET. Failure analysis proves that the low voltage silicon MOSFET is unaffected while the avalanche current flows through the SiC JFET gate which appears to be shorted.

Measurement and Modeling of Ambient-Air-Induced Degradation in Organic Thin-Film Transistor

The lifetime of organic thin-film transistors (OTFTs) is known to be significantly shorter than that of silicon MOSFETs. It is therefore important to be able to predict their degradation early in the design phase. In this paper, OTFT current characteristic variation is studied in measurements of fabricated devices. In addition, we propose a drain-current simulation model that incorporates temporal parameter variation. The proposed model expresses parameter degradations as changes in threshold voltage and carrier mobility. With the extracted parameters, our proposed model successfully reproduces the temporal performance degradation observed in fabricated devices. We compared our proposed model with existing parameter variation models by fitting with measurement results. Root mean square errors (RMSEs) were calculated for each model. Our proposed model achieved an RMSE of 2.26% whereas that of the existing model was 9.80%. Oscillation frequency degradation in an organic ring oscillator (RO) circuit was also simulated to compare with the measurement results. The simulation results adequately captured the degradation trend observed in the measured results.

Simulation-Based Ultralow Energy and High-Speed LIF Neuron Using Silicon Bipolar Impact Ionization MOSFET for Spiking Neural Networks

The silicon bipolar impact ionization MOSFET offers potential for the realization of leaky integrated fire (LIF) silicon neuron due to the presence of parasitic bipolar junction transistor (BJT) in the floating body. In this article, we have proposed an L-shaped gate bipolar impact ionization MOS (L-BIMOS) with reduced breakdown voltage ( ${V}_{B} = {1.68}$ V) and demonstrated the functioning of LIF neuron based on the positive feedback mechanism of parasitic BJT. Using the 2-D TCAD simulations, we manifest that the proposed L-BIMOS exhibits a low threshold voltage (0.2 V) for firing a spike, and the minimum energy required to fire a single spike for L-BIMOS is calculated to be 0.18 pJ, which makes the proposed device 194 times more energy efficient than the PD-SOI MOSFET silicon neuron and ${5}\times {10}^{{3}}$ times more energy efficient than the analog/digital circuit-based conventional neurons. Furthermore, the proposed L-BIMOS silicon neuron exhibits spiking frequency in the gigahertz range when the drain is biased at ${V}_{\text {DG}} = {2.0}$ V.

Wide Band Gap semiconductor material for electric vehicle charger

Electric vehicle technology is going to be the future of transportation, with the increase in technological advancement and the growing concerns on the greenhouse gas emission. The charging of electric vehicles is an important criterion for the fast commercialization of electric vehicles. The Wide Band Gap Semiconductor Material Based Power converter is gaining more attention; Since the increase in efficiency of PV and reduction in the cost of the PV module. This paper provides the theoretical guidelines to develop a high efficient reliable electric vehicle charging system. This paper presents the different areas to be concentrated for an efficient electric vehicle charging system and presented the need for wide bandgap semiconductor material for electric vehicle chargers. A comparison is made between silicon MOSFET versus silicon carbide and gallium nitride that has low power loss at high-frequency operation.

Investigation of Recessed Junctionless Double Gate MOSFET for Radio Frequency Applications

Junctionless Metal Oxide Semiconductor Field-Effect Transistor (JL MOSFET) is one of the promising candidate to replace the junction based MOSFET for upcoming technology nodes. Semiconductor industries are continuously urging for large ON current with the low OFF current and low specific on resistance. However, high ON current is achieved in Conventional (Conv.) JL DG MOSFET by using high doping concentration at the cost of high OFF current which leads depletion mode operation. Moreover, low doping, narrow channel thickness and high work function gate materials are using to operate Conv. JL DG MOSFET in enhancement mode (Vth > 0 V for N-JL DG MOSFET, Vth < 0 V for P-JL DG MOSFET) but ON current is reduced in all above mentioned solutions. To overcome the above mentioned problems, a new architecture is developed called Recessed JL DG MOSFET. In Recessed JL DG MOSFET silicon region is recessed under the gate region and some gate portion is extended towards source and drain region. Recessed JL DG MOSFET shows the same ON current as achieved in Conv. JL DG MOSFET with very low OFF current (leakage current) by considering high doping concentration. Surface potential, electron density, energy band distribution, drain current have been investigated to proof the enhancement mode operation of Recessed JL DG MOSFET. Figure of Merits (FOMs) for RF performance such as Trans-conductance, capacitance and intrinsic power gain (S21), Trans-conductance frequency product (TFP), Gain frequency product (GFP) and Gain trans-conductance frequency product (GTFP) have also investigated of Recessed JL DG MOSFET.

Performance of Various SiC Devices and their Behavior in DC/DC Converter

An extensive research on nano materials was carried out and the properties of Si were studied, Post study it was felt that there must be a material which exhibits semiconducting properties of Si with high breakdown voltage and work till high temperature range. Silicon Carbide (SiC) devices provided the answer for this. These devices are well known for high frequency, high voltage, high temperature and high power for their good material properties compared with silicon power MOSFET. In this paper, a study was conducted on various Silicon Carbide devices available in the market and the comparative performance of these devices were analysed. Furthermore there is a comparison of N channel silicon MOSFET device and silicon carbide device placed in bidirectional DC/DC buck converter in which Silicon Carbide device exhibit superior properties than Si device.

Performance and Reliability Review of 650 V and 900 V Silicon and SiC Devices: MOSFETs, Cascode JFETs and IGBTs

The future of power conversion at low-to-medium voltages (around 650 V) poses a very interesting debate. At low voltages (below 100 V), the silicon (Si) MOSFET reigns supreme and at the higher end of the automotive medium-voltage application spectrum (approximately 1 kV and above) the SiC power MOSFET looks set to topple the dominance of the Si insulated-gate bipolar transistor (IGBT). At very high voltages (4.5 kV, 6.5 kV and above) used for grid applications, the press-pack thyristor remains undisputed for current source converters and the press-pack IGBTs for voltage source converters. However, around 650 V, there does not seem to be a clear choice with all the major device manufacturers releasing different technology variants ranging from SiC Trench MOSFETs, SiC Planar MOSFETs, cascode-driven WBG FETs, silicon NPT and Field-stop IGBTs, silicon super-junction MOSFETs, standard silicon MOSFETs, and enhancement mode GaN high electron mobility transistors (HEMTs). Each technology comes with its unique selling point with gallium nitride (GaN) being well known for ultrahigh speed and compact integration, SiC is well known for high temperature, electro-thermal ruggedness, and fast switching while silicon remains clearly dominant in cost and proven reliability. This article comparatively assesses the performance of some of these technologies, investigates their body diodes, discusses device reliability, and avalanche ruggedness.

A New High-speed Drive Topology of Wide-bandgap Power MOSFET Based on Dynamic Procedure Model

More and more attention is being drawn on the wide-bandgap power MOSFET, for its performance is far superior to the traditional silicon MOSFET. Driving technology is one of the key factors that influence the performance of device. In this paper, a high-speed drive circuit topology is proposed. The principle of the improved drive circuit is simple and easy to be implemented. Compared with the traditional design, it can reduce the switching time while maintaining the original driving performance.