Accession Number : ADA319706

Title :   SiC Discrete Power Devices.

Descriptive Note : Annual technical rept. 15 Jan 96-14 Jan 97,

Corporate Author : NORTH CAROLINA STATE UNIV AT RALEIGH

Personal Author(s) : Baliga, B. J. ; Vijay, B. ; Shenoy, P. M. ; Davis, R. F. ; Tomozawa, H. S.

PDF Url : ADA319706

Report Date : 14 JAN 1997

Pagination or Media Count : 52

Abstract : A first order analysis was performed to determine the voltage-ratings upto which 4H-SiC, 6H-SiC unipolar devices (FETs) have lower forward voltage drops than silicon, 4H-SiC, 6H-SiC bipolar devices (IGBTs). It was found that 4H-SiC unipolar devices have the lowest forward voltage drops upto a voltage-rating of 4500V. The problems associated with a SiC power MOSFET are presented and alternatives to the power MOSFET, the JFET and the U-MESFET are discussed. Two dimensional simulations using MEDICI were performed to analyze the performance of a 1000V 4H-SiC U-MESFET. The U-MESFET was found to be an excellent device, with a low specific on-resistance close to the ideal value. The fabrication of a U-MESFET involves filling deep trenches with metal which is complicated. Further, when a metal gate is used, it is difficult to achieve gate to source isolation. A novel trench-gate heterojunction FET (FJFET) structure was analyzed to surpass this problem. The fabrication of the HJFET involves a six mask level process with no critical alignments. A process sequence for the fabrication of the HJFET was developed. The problems encountered during the fabrication and proposed solutions are outlined. Results of the experimental measurements on the fabricated HJFET are presented. A system has been fabricated for the chemical vapor deposition of 4H and 6H-SiC thin films. The unique design incorporates a separate load lock from which the growth chamber and a reflection high energy electron diffraction (RHEED) chamber are attached. Most of the system hardware has been assembled. Electrical wiring and gas line assembly has been completed to the extent possible. All power supply components have been received. Recently implemented safety concerns have resulted in the current retrofitting of newly assigned laboratory space to address these issues.

Descriptors :   *FIELD EFFECT TRANSISTORS, *SILICON CARBIDES, *MOSFET SEMICONDUCTORS, HETEROJUNCTIONS, GATES(CIRCUITS), CHEMICAL VAPOR DEPOSITION, ELECTRIC FIELDS, ELECTRICAL RESISTANCE, DOPING, BREAKDOWN(ELECTRONIC THRESHOLD), LOW VOLTAGE, HIGH VOLTAGE, BIPOLAR SYSTEMS.

Subject Categories : Electrical and Electronic Equipment

Distribution Statement : APPROVED FOR PUBLIC RELEASE