Search

The performance potentials and limits for GaN current aperture vertical electron transistors with conventional, doped, and natural polarization superjunction (PSJ) drift layers at 1.2–10 kV breakdown voltage (BV) ratings are quantitatively compared. The static and dynamic performance parameters for each device are simulated and extracted. The specific on‐resistance RON,sp and specific total charge QT,sp (defined as the sum of specific gate charge QG,sp and specific drain–source charge QDS,sp) are extracted from Medici technology computer‐aided design simulations representing both the static and dynamic performance respectively. Moreover, a developed figure‐of‐merit (FoM) (RON,sp · QT,sp) is used to quantitively compare the performance of these field‐effect transistors in the range of BV ratings. Compared to the doped superjunction (DSJ) and conventional CAVETs, natural PSJ CAVET exhibits 1%–60% and 70%–99% reduction in RON,sp, while it is 100 to 1000× reduction in QT,sp, at BV between 1.2 and 10 kV respectively. Simultaneously, 22%–80% and 80%–99% reduction in performance FoM respectively are found. [ABSTRACT FROM AUTHOR]

The effect of different gate oxide processes on the performance of 4H-SiC MOSFETs is analyzed. Various MOS device parameters, including threshold voltage, subthreshold slope, field-effect electron mobility, sheet electron carrier concentration and Hall mobility, are correlated with different process steps.

The performance of 4H-SiC planar junction barrier Schottky (JBS) rectifiers and lateral channel JBS (LC-JBS) rectifiers is described. The lateral channel JBS rectifier is designed and demonstrated in 4H-SiC with up to 1.5-kV blocking capability and pinlike reverse characteristics.

A new analytical model including both forward and reverse characteristics for high-voltage junction barrier Schottky (JBS) rectifiers is developed and applied to high-voltage SiC JBS rectifiers. The forward on-resistance of a high-voltage 4H-SiC JBS rectifier has many components, which are dominated by the spreading resistances in the drift layer.

Gallium nitride self-aligned MOSFETs were fabricated using low-pressure chemical vapor-deposited silicon dioxide as the gate dielectric and polysilicon as the gate material. The results indicated that GaN MOSFETs could be realized with promising electrical properties using a self-aligned process applicable to power integrated circuits.

A novel flip-chip flex-circuit packaging platform is described that enables integration of multiple power dies and control circuitry with an advantageous form factor. A key attribute of this packaging platform is to extend the well-established flex-circuit and flip-chip soldering technologies in signal electronics to power electronics applications. The planar interconnection and flip-chip method facilitate multilayer packaging structure with reduced packaging dimensions and reduced packaging parasitics. A half-bridge test vehicle designed and fabricated for dc/ac inverter applications (42 V, 16 A) with an overall flex-circuit module footprint less than 30% that of a discrete device printed circuit board implementation has been modeled and demonstrated experimentally. Electrical results, confirmed with circuit simulation incorporating parasitic inductance electromagnetic modeling, have shown a turn-off voltage overshoot reduction of over 40% and a switching energy loss reduction of 24% with the flip-chip flex-circuit implementation. The power flex platform has a strong potential for integrated multichip power module applications that require minimized packaging size and parasitic inductance for high switching frequency and efficiency. Index Terms--Flex-circuit, flip-chip, packaging parasitics, power electronics packaging, switching energy loss, voltage overshoot.

Recent progress in silicon carbide (SIC) material has made it feasible to build power devices of reasonable current density. This paper will present recent results including a comparison with state-of-the-art silicon diodes. Switching losses for two silicon diodes (a fast diode, 600 V, 50 A, 60 ns Trr), an ultrafast silicon diode (600 V, 50 A, 23 ns Trr), and a 4H-SiC diode (600 V, 50 A) are compared. The effect of diode reverse recovery on the turn-on losses of a fast insulated gate bipolar transistor (IGBT) are studied both at room temperature and at 150 [degrees]C. At room temperature, SiC diodes allow a reduction of IGBT turn-on losses by 25% compared to ultrafast silicon diodes and by 70% compared to fast silicon diodes. At 150 [degrees]C junction temperature, SiC diodes allow turn-on loss reductions of 35% and 85% compared to ultrafast and fast silicon diodes, respectively. The silicon and SiC diodes are used in a boost converter with the IGBT to assess the overall effect of SiC diodes on the converter characteristics. Efficiency measurements at light load (100 W) and full load (500 W) are reported. Although SiC diodes exhibit very low switching losses, their high conduction losses due to the high forward drop dominate the overall losses, hence reducing the overall efficiency. Since this is an ongoing development, it is expected that future prototypes will have improved forward characteristics. Index Terms--4H-SiC, carbide, diode, insulated gate bipolar transistor (IGBT), recovery, reverse, silicon, silicon carbide (SIC).

GaN metal oxide semiconductor (MOS) capacitors are used to investigate the effects of annealing temperature and ambient on GaN-insulator interface properties.

SiC P-i-N rectifiers possess forward characteristics that exhibit current-controlled negative resistance. The forward characteristics of 6H-SiC P-i-N rectifiers suggest that the poor electrical performance of SiC diodes can be attributed to the absence of conductivity modulation. This behavior appears to result from high defect densities and low minority carrier lifetime in the lightly doped drift region.

6H-SiC P(super +)N layers have been fabricated using beryllium as an alternate p-type dopant. The implanted junctions have been characterized by photoluminescence and secondary ion mass spectrometry. Experimental results showed that beryllium-implanted 6H-SiC P(super +)N junctions exhibit improved forward characteristics and slightly higher reverse leakages. The activation energies obtained from the forward conduction and reverse leakage characteristics were presented.