Spectroscopic Properties of Cubic SiC on Si
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Spectroscopic Properties of Cubic SiC on Si Z. C. Feng,1,* D. N. Talwar2 and I. Ferguson1 1
School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0250, USA 2 Department of Physics, Indiana University of Pennsylvania, Indiana, PA 15705-1087, USA ABSTRACT Spectroscopic studies are reported for cubic SiC grown on Si by chemical vapour deposition (CVD) manufacture technique. The UV excitation room temperature photoluminescence (PL)Raman spectra exhibited 2.3 eV luminescence line due to RT recombination over the SiC indirect band gap. In addition to the optical phonons from cubic SiC we observed new Raman modes near 620 and 833 cm-1. A comprehensive analysis of the dynamical properties of defects using Green’s function theory has suggested isolated impurity vibrations to be the possible origin for the additional phonons observed by Raman spectroscopy.
INTRODUCTION Silicon carbide (SiC) is a valuable semiconductor material for electronic and optical devices working at high temperature, high radiation flux and other severe environments. Cubic (3C or β) SiC is particularly attractive because it possesses large energy gap (~ 2.2 eV at room temperature), high electric breakdown field, high saturation drift velocity, chemical inertness, and zinc-blende structure [1, 2]. Despite the mismatch in lattice constants (~20%) and the difference in thermal expansion coefficients (~8%) between 3C-SiC and Si, large size 3C-SiC/Si films have been grown successfully by CVD technique [3-6]. The use of SiC in electronic devices has substantially increased in recent years due to the progress in epitaxially growth methods, availability of larger size wafers and high quality 6Hand 4H-SiC substrates [7]. It is true that the current developments in device applications using SiC are focused on 6H- and 4H-SiC, the 3C-SiC/Si material system is attractive due to its special advantages over the hexagonal poly types. These include its low cost in comparison with 6Hand 4H-SiC, an excellent performance for microwave devices with high (~400oC) temperature high power output 67 kW/cm2 operations (30 times larger than the devices made from GaAs [8]), and the promise it holds as a substrate for the epitaxial growth of group III-nitrides [9-11]. The electronic devices based on 3C-SiC/Si material systems are proven to be readily combined with Si devices and commercially manufactured owing to its compatibility with advanced Siprocessing technology [12-15]. In this work, we report the spectroscopic properties of 3C-SiC/Si films grown by CVD. UV excitation room temperature PL-Raman spectra have exhibited a luminescence band near 2.3 eV due to RT recombination over the 3C-SiC indirect band gap. In addition to the optical phonons from cubic SiC, the Raman scattering spectra revealed extra modes at 620 and 833 cm-1. A comprehensive analysis of the dynamical properties of defects by Green’s function theory has suggested isolated impurity modes as possible explanation for the additional Raman lines. *
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