Zachary Stum

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.

4H-SiC n-Channel Insulated Gate Bipolar Transistors on (0001) and (000-1) Oriented Free-Standing n − Substrates

We experimentally demonstrate 4H-SiC n-channel, planar gate insulated gate bipolar transistors (IGBTs) on 180-μm thick lightly doped free-standing n- substrates with ion-implanted collector regions, and metal-oxide-semiconductor gates on (0001) and (000-1) surfaces. The IGBTs show an ON-state current density of 20 A/cm2 at a power dissipation of 300 W/cm2. The threshold voltages are measured to be 7.5 V and 10.5 V on Si-face and C-face, respectively. Both IGBTs show a small positive temperature coefficient of the forward voltage drop, which is useful for easy parallelization of devices.

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.

DC and Transient Performance of 4H-SiC Double-Implant MOSFETs

SiC vertical MOSFETs were fabricated and characterized, achieving blocking voltages around 1 kV and specific on-resistances as low as RSP,ON=8.3 mOmegamiddotcm2. DC and transient characteristics are shown. Room and elevated temperature (up to 200degC) 600 V/5 A inductive switching performance of the SiC MOSFETs are shown with turn-on and turn-off transients of approximately 20-40 ns.

300°C Silicon Carbide Integrated Circuits

MOSFET-based integrated circuits were fabricated on silicon carbide (SiC) substrates. SiC devices can operate at much higher temperatures than current semiconductor devices. Simple circuit components including operational amplifiers and common source amplifiers were fabricated and tested at room temperature and at 300°C. The common source amplifier displayed gain of 7.6 at room temperature and 6.8 at 300°C. The operational amplifier was tested for small signal open loop gain at 1kHz, measuring 60 dB at room temperature and 57 dB at 300°C. Stability testing was also performed at 300°C, showing very little drift at over 100 hours for the individual MOSFETs and the common source amplifier.

3kV 4H-SiC Thyristors for Pulsed Power Applications

Due to the Silicon Carbide (SiC) material’s high electric field strength, wide bandgap, and good thermal conductivity, 4H-SiC thyristors are attractive candidates for pulsed power applications. With a thinner blocking layer almost an order of magnitude smaller than its Silicon (Si) counterpart, these devices promise very fast turn-on capabilities as full conductivity modulation occurs >10 times faster than comparable silicon thyristors, low leakage currents at high junction temperatures and at high voltage, and much lower forward voltage drop at high pulse currents. Our progress on the development of large area (4mm x 4mm) SiC thyristors is presented in this paper.

Realizing the full potential of silicon carbide power devices

Silicon carbide (SiC) MOSFET power devices are expected to replace silicon IGBTs in power electronics applications requiring higher efficiency and power density, as well as capability to operate at higher temperatures. This paper reports on the development of high efficiency SiC power MOSFETs, power modules and switching converters at GE. The prototype 30A, 1200V discrete devices have on-resistance below 50 mΩ and the total switching energy of 0.6 mJ, offering performance superior to any competing 1200V devices. A back-to-back buck-boost converter was built using 15A MOSFETs and experimental results are presented. The 15A devices were also used for fabrication of 150A all-SiC modules. The modules have 10 mΩ on-resistance and the total switching energy is 3.3 mJ, both significantly better than competing designs. The results demonstrate the full potential of the SiC devices for power conversion applications.

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.

100 Amp, 1000 Volt Class 4H-Silicon Carbide MOSFET Modules

The development of large area, up to 70m/1kV (0.45cm x 0.45cm) 4H-SiC vertical DMOSFETs is presented. DC and switching characteristics of high-current, 100Amp All-SiC power switching modules are demonstrated using 0.45cm x 0.225cm DMOSFET die and commercial Schottky diodes. The switching performance from room temperature up to T=200°C of the All-SiC modules is presented, with as much as ten times lower losses than co-fabricated Si-based modules using commercial IGBTs.