Characterization of 4H <000-1> Silicon Carbide Films Grown by Solvent-Laser Heated Floating Zone
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Characterization of 4H Silicon Carbide Films Grown by Solvent-Laser Heated Floating Zone Andrew A. Woodworth1, Ali Sayir2, Philip G. Neudeck3, Balaji Raghothamachar4 and Michael Dudley4 1
NASA Postdoctoral Program Fellow, NASA Glenn Research Center, 21000 Brookpark Road, MS 106-1, Cleveland, OH 44135, USA 2
NASA Glenn Research Center, 21000 Brookpark Road, MS 106-1, Cleveland, OH 44135, USA
3
NASA Glenn Research Center, 21000 Brookpark Road, MS 77-1, Cleveland, OH 44135, USA
4
Department of Materials Science & Engineering, Stony Brook University, Stony Brook, NY 11794-2275, USA ABSTRACT Commercially available bulk silicon carbide (SiC) has a high number (>2000/cm2) of screw dislocations (SD) that have been linked to degradation of high-field power device electrical performance properties. Researchers at the NASA Glenn Research Center have proposed a method to mass-produce significantly higher quality bulk SiC. In order for this bulk growth method to become reality, growth of long single crystal SiC fibers must first be achieved. Therefore, a new growth method, Solvent-Laser Heated Floating Zone (Solvent-LHFZ), has been implemented. While some of the initial Solvent-LHFZ results have recently been reported, this paper focuses on further characterization of grown crystals and their growth fronts. To this end, secondary ion mass spectroscopy (SIMS) depth profiles, cross section analysis by focused ion beam (FIB) milling and mechanical polishing, and orientation and structural characterization by X-ray transmission Laue diffraction patterns and X-ray topography were used. Results paint a picture of a chaotic growth front, with Fe incorporation dependant on C concentration. INTRODUCTION The use of silicon carbide (SiC) power electronics are widely accepted to be capable of enabling systems that are significantly lighter, smaller, and electrically more efficient than systems comprised of conventional silicon (Si) based electronics. Although some SiC devices (e.g., Schottky diodes and field-effect transistors (FETs)) have been developed, the performance of most SiC power devices are significantly degraded/limited because of a high density of crystal defects in all commercially-available SiC semiconductor wafers. Among the more serious defects in these SiC wafers is a defect known as a “closed-core” screw dislocation (SD), with densities typically greater than 2000 per cm2 [1-3]. Eliminating these dislocation defects (i.e., reducing them to densities < 1 per cm2) would unlock more of SiC’s enormous (as yet unfulfilled) promise to revolutionize nearly all high-power electronic systems.
Recently, SiC growth perpendicular to the c-axis has been shown to grow higher quality (lower defect density) bulk SiC [4]. Researchers at the NASA Glenn Research Center have proposed a method to mass-produce high quality bulk SiC [5]. This technique starts by growing a long continuous single crystal SiC fiber in the crystallographic c-direction, and then laterally (perpendicular to the c-direction) enlarging the fiber into a high qual
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