Comparison of 3C-SiC Films Grown By CVD on Si(111) and Si(211) Substrates
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Comparison of 3C-SiC Films Grown By CVD on Si(111) and Si(211) Substrates B. A. Grayson,1 J. T. Wolan,1* M. Graves,1 M. Bledsoe,2 K. Kirchner 3 and S. E. Saddow 2 1
Dave C. Swalm School of Chemical Engineering, Mississippi State, MS 39762-9595
2
Emerging Materials Research Laboratory, Dept of ECE, Mississippi State, MS 39762-9571
3
Sensors and Electron Devices Directorate, Army Research Laboratory, Adelphi, MD 207831197 *Corresponding author Abstract In this study, the near-surface region of air-exposed thin 3C-SiC films grown on 50-mm (2-in.) diameter Si(111) and Si(211) substrates have been investigated. Carbonization to create the film in a radio-frequency (RF) induction-heated horizontal atmospheric-pressure chemicalvapor-deposition reactor utilized a propane-hydrogen mix (3% C3H8 in ultra-high purity hydrogen) with a hydrogen carrier. Elemental and chemical-state identification of the thin-films are presented. Several structure sensitive techniques including X-UD\GLIIUDFWLRQ ;5' LQ - as well as scanning electron microscopy (SEM) to examine crystal structure, surface morphology and film thickness are included. Introduction This initial motivation of this project was to evaluate the potential device characteristics of 3C-SiC epitaxial layers grown on silicon substrates. Some of the beneficial properties of 3CSiC that could be coupled with current silicon technology are that it is a wide band gap material, it is very robust under harsh environments, it has low-temperature stability, and that it has the highest electron mobility of all the SiC polytypes [1]. However, many attempts have been made for years to grow high quality 3C-SiC on silicon with no success. Currently, 3C-SiC on silicon has not been grown on silicon without serious defects such as large numbers of twinning defects in 3C-SiC grown on (100)Si, which are a result of the high degree of lattice mismatch between the two substances [2]. High defect concentrations of 3C-SiC on Si substrates have proven that it limits 3C-SiC/Si uses for device applications [3]. Researchers attest to the fact that 3C-SiC epitaxial film quality is improved when deposited upon on-axis crystal planes [4]. The hypothesis of this experiment is that off-axis oriented Si substrates may offer improved growth surface for 3C-SiC films due to the additional template information afforded by the threedimensional surface, and therefore, improving its device characteristics. The steps formed by cleaving the substrate at an angle will provide areas of strain relief that will allow the dissimilar Si and SiC to relieve some of the stress caused by the different lattice constants. Two silicon substrates were compared in this experiment; one substrate was cleaved along the (111) plane while the other was cleaved along the (211) plane. Initially, both substrates were coated with a layer of carbon to provide a buffer layer for the epitaxial 3C-SiC layer. The one-hour 3C-SiC growth runs were performed in the Emerging Materials Research Laboratory located on the
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