Showing papers by "John W. Palmour published in 1994"

Conductivity Anisotropy in Epitaxial 6H and 4H Sic

Abstract: A measure of the electron mobility anisotropy in n-type 4H and 6H-SiC has been obtained using the Hall effect over the temperature range 80K

Method of obtaining high quality silicon dioxide passivation on silicon carbide and resulting passivated structures

Abstract: A method of obtaining high quality passivation layers on silicon carbide surfaces by oxidizing a sacrificial layer of a silicon-containing material on a silicon carbide portion of a device structure to substantially consume the sacrificial layer to produce an oxide passivation layer on the silicon carbide portion that is substantially free of dopants that would otherwise degrade the electrical integrity of the oxide layer.

4H-SiC MESFET with 2.8 W/mm power density at 1.8 GHz

Abstract: MESFET's were fabricated using 4H-SiC substrates and epitaxy The DC, S-parameter, and output power characteristics of the 07 /spl mu/m gate length, 332 /spl mu/m gate width MESFET's were measured At /spl nu//sub ds/=25 V the current density was about 300 mA/mm and the maximum transconductance was in the range of 38-42 mS/mm The device had 93 dB gain at 5 GHz and f/sub max/=129 GHz At V/sub ds/=54 V the power density was 28 W/mm with a power added efficiency=127% >

SiC MOS interface characteristics

Abstract: It is well known that SiC can be thermally oxidized to form SiO/sub 2/ layers. And Si MOSFET IC's using thermally grown SiO/sub 2/ gate dielectrics are the predominant IC technology in the world today. However the SiC/SiO/sub 2/ interface has not been well characterized as was the case for Si MOS in the early 1960's. This paper presents data which for the first time characterizes the SiC/SiO/sub 2/ interface and explains one of the previously unexplained abnormalities observed in the characteristics of SiC MOSFET's. >

High Power and High Frequency Silicon Carbide Devices

Abstract: The breakdown electric field of 4H-SiC as a function of doping was measured using pn junction rectifiers, with maximum voltages of 1130 V being achieved. 4H-SiC vertical power MOSFET structures have shown specific on-resistances of 33 mΩ-cm2 for devices capable of blocking 150 V. A current density of 100 A/cm2 was achieved at a drain voltage of 3.3 V. Thyristors fabricated in SiC have also shown blocking voltages of 160 V and 100 A/cm2 at 3.0 V. High temperature operation was measured, with the power MOSFETs operating to 300°C, and the thyristors operating to 500°C. Submicron 6H- and 4H-SiC MESFETs have shown good I-V characteristics to Vd= 40 V, with an Idss of 200-300 mA/mm. The maximum operating frequencies (fmax) achieved for 6H-SiC MESFETs is 13.8 GHz, with small-signal power gains of 9.8 dB and 2.9 dB at 5 GHz and 10 GHz, respectively. 4H-SiC MESFETs have demonstrated an RF output power density of 2.8 W/mm at 1.8 GHz. This is the highest power density ever reported for SiC and is 2-3 times higher than reported for comparable GaAs devices.

4H-silicon carbide mesfet with 2.8 W/mm rf power density

Abstract: Silicon carbide has tremendous potential for high power microwave devices because of its high breakdown electric field (4x106 V/cm), high thermal conductivity (4.9 W/cm-K), high saturated electron drift velocity ( 2 . 0 ~ 107 cm/sec) and low dielectric constant (10.0). The high velocity allows the devices to operate at relatively high frequencies despite the low mobility of S i c . The high breakdown field allows about ten times higher voltages to be applied for a given channel doping, which should allow a much higher output power density to be achieved than with Si or GaAsl . Submicron MESFETs have been previously fabricated in 6H-Sic and have shown desirable microwave performance with RF output powers of about 1 W/mm at 1-2 G H Z ~ ~ ~ . However, another polytype, 4H-SiC, shows even more potential for high power, high frequency operation, because its electron mobility (>550 cm2/V-sec) is about twice that of 6H-Sic. Thus we report the first DC, S-parameter, and output power results obtained with 4H-Sic MESFETs.