C.D. Brandt

1.1 kV 4H-SiC power UMOSFETs

Silicon Carbide (4H-SiC), power UMOSFETs were fabricated and characterized from room temperature to 200/spl deg/C. The devices had a 12-/spl mu/m thick lightly doped n-type drift layer, and a nominal channel length of 4 /spl mu/m. When tested under Fluorinert/sup TM/ at room temperature, blocking voltages ranged from 1.0 kV to 1.2 kV. Effective channel mobility ranged from 1.5 cm/sup 2//V.s at room temperature with a gate bias of 32 V (3.5 MV/cm) up to 7 cm/sup 2//V.s at 100/spl deg/C with an applied gate bias of 26 V (2.9 MV/cm). Specific on-resistance (R/sub on,sp/) was calculated to be as low as 74 m/spl Omega/.cm/sup 2/ at 100/spl deg/C under the same gate bias.

700-V asymmetrical 4H-SiC gate turn-off thyristors (GTO's)

Silicon Carbide (4H-SiC), asymmetrical gate turn-off thyristors (GTOs) were fabricated and tested with respect to forward voltage drop (V/sub F/), forward blocking voltage, and turn-off characteristics. Devices were tested from room temperature to 350/spl deg/C in the dc mode. Forward blocking voltages ranged from 600-800 V at room temperature for the devices tested. V/sub F/ of a typical device at 350/spl deg/C was 4.8 V at a current density of 500 A/cm/sup 2/. Turn-off time was less than 1 /spl mu/s. Although no beveling or advanced edge termination techniques were used, the blocking voltage represented approximately 50% of the theoretical value when tested in an air ambient. Also, four GTO cells were connected in parallel to demonstrate 600-V, 1.4 A (800 A/cm/sup 2/) performance.

Large diameter 6H-SiC for microwave device applications

6H-polytype SiC single crystals with diameters up to 50 mm and lengths up to 75 mm have been grown in the c-and a-axis directions by physical vapor transport (PVT) at growth rates of 0.25 to 1 mm h -1 . Undoped crystals grown from purified source material reveal residual impurity concentrations in the 10 16 cm -3 range and resistivities up to 1000 Ω-cm. N + crystals with resistivities < 0.02 Ω-cm have been produced by controlled nitrogen doping. PVT-grown SiC crystals are characterized by dislocation densities of 10 4 to 10 5 cm -2 and can also exhibit micropipe defects in the 10 2 to 10 3 cm -2 range

4H-SiC MESFET's with 42 GHz f/sub max/

We report for the first time the development of state-of-the-art SiC MESFETs on high-resistivity 4H-SiC substrates. 0.5 /spl mu/m gate MESFETs in this material show a new record high f/sub max/ of 42 GHz and RF gain of 5.1 dB at 20 GHz. These devices also show simultaneously high drain current, and gate-drain breakdown voltage of 500 mA/mm, and 100 V, respectively showing their potential for RF power applications.

RF performance of SiC MESFET's on high resistivity substrates

State-of-the art SiC MESFETs showing a record high f/sub max/ of 26 GHz and RF gain of 8.5 dB at 10 GHz are described in this paper. These results were obtained by using high-resistivity SiC substrates for the first time to minimize substrate parasitics. The fabrication and characterization of these devices are discussed.<<ETX>>

High power 4H-SiC static induction transistors

Static induction transistors have been demonstrated in 4H-SiC. SiC specific semiconductor processing technologies such as epitaxy, reactive ion etching, and sidewall Schottky gates were employed. Under pulsed power test conditions, 4H-SiC SITs developed a maximum output power of 225 W at 600 MHz, a power added efficiency of 47%, and a gain of 8.7 dB. Maximum channel current was 1 A/cm, and the maximum blocking voltage was 200 V.

30 W VHF 6H-SiC power static induction transistor

6H-SiC Static Induction Transistors (SITs) have been demonstrated, using SiC specific semiconductor processing technologies such as, VPE, reactive ion etching and self aligned sidewall Schottky gates. Under test conditions, 6H-SiC SITs developed 38 W of output power at 175 MHz, a power added efficiency of 60%, and an associated gain of 10 dB. The maximum channel current was 300 mA/cm, and the maximum blocking voltage was 200 V.

Advances in silicon carbide (SiC) device processing and substrate fabrication for high power microwave and high temperature electronics

High-power density, temperature tolerant silicon carbide (SiC) electronics offer an exceptional opportunity to increase the performance and lower the cost of many existing and emerging military and commercial products. Surveillance and tactical radar systems, compact electric tank and aircraft engine controls, high reliability aviation electronics, and radiation resistance satellite components are some examples. Recent technology advances have brought this potential payoff closer to reality. These include the fabrication of a record-setting MESFET device with 12 dB gain at 2 GHz and 2 W/mm of power at 1 GHz and the worlds first 2-inch diameter high-resistivity SiC wafers for planar devices and low resistivity substrates for power devices. Vertical transistor structures have also been fabricated using both Schottky barrier and MOS gates.<<ETX>>

SiC High Temperature Electronics for Next Generation Aircraft Controls Systems

Several organizations, including Westinghouse, CREE, and ATM, as well as researchers in Japan and Europe, are working to develop SiC power devices for reliable, high power and high temperature environments in military, industrial, utility, and automotive applications. Other organizations, such as NASA Lewis and several universities, are also doing important basic work on basic SiC technology development. It has been recognized for two decades that the superior properties of SiC lead to range of devices with higher power, greater temperature tolerance, and significantly more radiation hardness than silicon or GaAs. This combination of superior thermal and electrical properties results in SiC devices that can operate at up to ten times the power density of Si devices for a given volume.Recent research has focused on the development of vertical metal oxide semiconductor field effect transistor (VMOSFET) power device technology, and complementary high speed, temperature-tolerant rectifier-diodes for power applications. We are also evaluating applications for field control thyristors (FCT) and MOS turn-off thyristors (MTO). The technical issues to be resolved for these devices are also common to other power device structures. The present paper reviews the relative benefits of various power devices structures, with emphasis on how the special properties of SiC enhance the desirability of specific device configurations as compared to the Si-based versions of these devices. Progress in SiC material quality and recent power device research will be reviewed, and the potential for SiC-based devices to operate at much higher temperatures than Si-based devices, or with enhanced reliability at higher temperatures will be stressed. We have already demonstrated 1000V breakdown, current densities of 1 kA/cm2, and measurements up to 400°C in small diodes. The extension of this work will enable the implementation of highly distributed aircraft power control systems, as well as actuator and signal conditioning electronics for next generation engine sensors, by permitting electronic circuits, sensors and smart actuators to be mounted on or at the engine.Copyright