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This paper presents the latest 1.2kV-2.2kV SiC MOSFETs designed to maximize SiC device benefits for highpower, medium voltage power conversion applications. 1.2kV, 1.7kV and 2.2kV devices with die size of 4.5mm x 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/cm 2 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 o C and 11mOhm at 150 o C. The module exhibits 9mJ turn-on and 14mJ turn-off losses at Vds=900V, Id=400A. Validation of GE's SiC MOSFET performance advantages was done through continuous buckboost 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.

The physical vapor transport technique can be employed to fabricate large diameter silicon carbide crystals (up to 50 mm diameter) exhibiting uniform 4H‐polytype over the full crystal volume. Crystal growth rate is controlled to first order by temperature conditions and ambient pressure. 4H‐polytype uniformity is controlled by polarity of the seed crystal and the growth temperature. 4H‐SiC crystals exhibit crystalline defects mainly in the form of dislocations with densities in the 104 cm—2 range and micropipe defects, the latter having densities as low as 10 cm—2 in best crystals. Electrical conductivity in 4H‐SiC bulk crystals ranges from <10—2 Ω cm, n‐type, to insulating (>1015 Ω cm) at room temperature.

The properties of the SiO2∕GaN interface were characterized using metal-oxide-semiconductor capacitors on polar c-plane (0001) and nonpolar m-plane (0 1 -1 0) GaN crystal faces. GaN m-plane samples show the absence of pyroelectric polarization effects. Additionally, capacitance-voltage hysteresis is less on m-plane compared to c-plane GaN surfaces, suggesting a lower interface-state density at the m-plane GaN∕SiO2 interface.

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