Structural Characterization of Sic Epitaxial Layers Grown on Porous Sic Substrates
- PDF / 2,797,826 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 77 Downloads / 201 Views
STRUCTURAL CHARACTERIZATION OF SIC EPITAXIAL LAYERS GROWN ON POROUS SIC SUBSTRATES S. E. Saddow,1 G. Melnychuk,1 M. Mynbaeva,2 I. Nikitina,2 W. M. Vetter,3 L. Jin,3 M. Dudley,3 M. Shamsuzzoha,4 V. Dmitriev,5 and C. E. C. Wood 6 1
Emerging Materials Research Laboratory, Dept. of ECE, Mississippi State, MS 39762-9571 Ioffe Institute, St. Petersburg, 194021 Russia 3 Dept. of Materials Science, SUNY-Stony Brook, Stony Brook, NY 4 Dept. of Metallurgical Engr. & School of Mines Energy Dev., University of Alabama, Tuscaloosa, AL 35487 5 TDI, Inc, Gaithersburg, MD, 20877 6 Office of Naval Research, 800 N. Quincy St., Arlington, VA 22217 USA 2
ABSTRACT A layer of porous SiC was fabricated by surface anodization of commercial 4H and 6H-SiC (0001)Si face off-axis wafers. A 8.5 µm 4H-SiC epilayer was grown on porous SiC (PSC) substrates using atmospheric pressure CVD. TEM investigation on cross-sectional specimens of the CVD epitaxial layers revealed that the presence of pores in the substrate does not lead to the formation of any micropipe in the epitaxial layer. The investigation also failed to detect a more than usual dislocation density on the basal plane of the epitaxial layer. Based upon the results of various analytical techniques applied to the CVD deposit we propose that the density of screw dislocations in the epitaxial layer is less than 5x104 cm-3. It should be noted that the density of similar types of dislocations in the initial substrate as determined by the TEM was ~106 cm-3, so this preliminary investigation indicates that the epitaxial layer grown on PSC may have a reduction in dislocation density of more than an order of magnitude over those grown on conventional SiC substrates that are not porous. Synchrotron white beam x-ray topography (SWBXT) was performed on these layers. Comparison between the dislocation density on the porous and standard epitaxial layers proved to be very similar using this technique. INTRODUCTION The presence of micropipes and dislocations in SiC wafers used as substrates for SiC epitaxial growth may cause formation of lattice defects in the epilayers. The objective of this research was to characterize epitaxial layers grown by chemical vapor deposition (CVD) on porous SiC (PSC) buffer layers [1] in order to determine the quality of these epitaxial layers. PSC has been developed for numerous applications, such as power device passivation [2], and as buffer layers for GaN epitaxial growth [3]. PSC buffer layers were formed on one half of the surface of conventional 4H-SiC substrates via the anodization of the substrate in an aqueous HF solution [2]. The PSC layer was observed to extend approximately 5 µm into the SiC substrate thus forming a PSC buffer layer for subsequent epitaxial layer growth [4]. Using a horizontal cold-wall chemical vapor deposition (CVD) system, a 8.5 µm thick SiC epitaxial layer was grown simultaneously on both PSC and standard (i.e., ‘control’) substrates using a standard dual-precursor CVD growth technique described elsewhere [5]. The substrate H2.7.1
was
Data Loading...
