Alexander Viktorovich Bolotnikov

3.3kV SiC MOSFETs designed for low on-resistance and fast switching

This paper discusses the latest developments in the optimization and fabrication of 3.3kV SiC vertical DMOSFETs. The devices show superior on-state and switching losses compared to the even the latest generation of 3.3kV fast Si IGBTs and promise to extend the upper switching frequency of high-voltage power conversion systems beyond several tens of kHz without the need to increase part count with 3-level converter stacks of faster 1.7kV IGBTs.

Overview of 1.2kV – 2.2kV SiC MOSFETs targeted for industrial power conversion applications

This paper presents the latest 1.2kV-2.2kV SiC MOSFETs designed to maximize SiC device benefits for high-power, medium voltage power conversion applications. 1.2kV, 1.7kV and 2.2kV devices with die size of 4.5mm × 4.5mm were fabricated, exhibiting room temperature on-resistances of 34mOhm, 39mOhm and 41mOhm, respectively. The ability to safely withstand single-pulse avalanche energies of over 17J/cm2 is demonstrated. Next, the 1.7kV SiC MOSFETs were used to fabricate half-bridge power modules. The module typical onresistance was 7mOhm at Tj=25°C and 11mOhm at 150°C. The module exhibits 9mJ turn-on and 14mJ turn-off losses at Vds=900V, Id=400A. Validation of GEs SiC MOSFET performance advantages was done through continuous buck-boost operation with three 1.7kV modules per phase leg exhibiting 99.4% efficiency. Device ruggedness and tolerance to terrestrial cosmic radiation was evaluated. Experimental results show that higher voltage devices (2.2kV and 3.3kV) are more susceptible to cosmic radiation, requiring up to 45% derating in order to achieve module failure rate of 100 FIT, while 1.2kV MOSFETs require only 25% derating to deliver similar FIT rate. Finally, the feasibility of medium voltage power conversion based on series connected 1.2kV SiC MOSFETs with body diode is demonstrated.

1.2kV class SiC MOSFETs with improved performance over wide operating temperature

In this paper, we report on 1.2kV SiC MOSFETs rated to T_{j, max}=200°C, exhibiting improved performance characteristics across operating temperature. Our devices show stable, rugged and reliable operation when subjected to industry standard qualification tests. Low on-resistance of 35mOhm/79mOhm at T_j=25°C and 47mOhm/103mOhms at T_j=150°C are shown for 0.1cm² and 0.2cm² die. 1000 hour High-Temperature Gate-Bias (HTGB) tests at T_j=200°C show excellent threshold stability with less than 5% parametric shift observed. High-Temperature Reverse Bias (HTRB) at T_j=200°C/V_DS=960V also show stable and reliable operation. Single-pulse avalanche energies of over E_Av=1.75J are obtained with 0.1cm² MOSFETs.

High performance SiC MOSFET module for industrial applications

A novel 1.7kV, 500A low inductance half-bridge module has been developed for fast-switching SiC devices. The module has a maximum temperature rating of 175°C. There are 12 GE SiC MOSFET chips per switch and the MOSFETs body diode is utilized as the freewheeling diode. The modules typical on-resistance is 3.8mOhms at 25°C and 5.8mOhms at 175°C. Internal loop inductance measured from DC input terminals is 4.5nH, approximately 75% lower than that of a standard IGBT module. When connected to a low inductance busbars, the module can be switched in 50ns without excessive voltage and current overshoots. Double pulse inductive switching losses at VDS=1000V, Id=450A and TJ=150°C are: EON=21.5mJ, EOFF=16.5mJ and EREC=6mJ. The losses are at least ten times lower when compared to a similarly rated IGBT module, highlighting the SiC advantage for higher switching frequency applications. Short circuit testing was performed, demonstrating good ruggedness albeit the need for a fast protection circuit.

Static and dynamic characterization of 6.5kV, 100A SiC Bipolar PiN Diode modules

High voltage and high current SiC bipolar diode modules are fabricated and characterized under static and dynamic conditions. The modules are built using 6×6mm2 SiC chips that are fabricated on 3″ SiC substrates. Individual chips were also packaged in an ISOPLUS™ package and used to perform switching tests on the diodes. The modules have been fully characterized under static and dynamic conditions. These modules are targeted for high voltage, high frequency applications, as well as antiparallel diodes for 6.5kV IGBTs, IGCTs, and IEGTs.

4kV Silicon Carbide MOSFETs

Doubly-implanted SiC vertical MOSFETs were fabricated displaying a blocking voltage of 4.2kV and a specific on-resistance of 23 mΩ-cm2, on a 4.5mm x 2.25mm device. Design variations on smaller (1.1mm x 1.1mm) devices showed on-resistance as low as 17 mΩ-cm2 with a blocking voltage of 3.3kV. Analysis is presented of the on-resistance and temperature dependence (up to 175°C), as well as switching performance. Switching tests taken at 1000V and 6A showed turn-on and turn-off transients of approximately 20-40ns.

Silicon carbide photomultipliers and avalanche photodiode arrays for ultraviolet and solar-blind light detection

Silicon carbide is known for its large bandgap and suitability to make highly sensitive ultraviolet photo-detectors. These devices show appreciable quantum efficiencies in the 240 nm – 350 nm wavelength range in combination with low dark currents. We present recent results on 4H-SiC avalanche photodiode arrays and SiC-based solid-state photomultiplier arrays suitable for ultraviolet and solar-blind light detection. A novel SiC-based photomultiplier array was demonstrated. Additional solar-blind optical filter allowed achieving a solar photon rejection ratio of more than 106 in combination with 40% quantum efficiency at 280 nm. More than 50% of pixels of the array have demonstrated low dark count rates in the range of several kHz and single photon detection efficiencies of more than 30% at 266 nm in the solar-blind wavelengths range. The photomultiplier array operating in Geiger mode has demonstrated a linearly increasing response with an increase in number of incident photons. We report on the electrical and optical characteristics of solar-blind 4H-SiC avalanche photodiode arrays and photomultipliers.

Long Carrier Lifetime in 4H-SiC Epilayers Using Chlorinated Precursors

In this work we report the measurement of minority carrier lifetimes using the time resolved photoluminescence technique. It was found that 4H-SiC homo-epilayers grown using chlorine-based precursors have longer carrier lifetimes if used in conjunction with a tantalum carbide coated (TaC-coated) graphite susceptor rather than a SiC-coated graphite susceptor. Longer carrier lifetimes were obtained by optimal combinations of precursor gases and susceptor type. The controllable variation in lifetime from 250 ns to 9.9 s was demonstrated.

Design of Area-Efficient, Robust and Reliable Junction Termination Extension in SiC Devices

This paper discusses SiC JTE design tradeoffs required to maximize device performance while minimizing consumed die area, fabrication cost and maintaining good reliability. Modeling and experimental results are provided.

Utilization of SiC MOSFET Body Diode in Hard Switching Applications

This work discusses the possibility of using SiC MOSFET body diode in switching power conversion applications, focusing on performance and reliability aspects.