Homoepitaxial Growth of Vanadium-Doped Semi-insulating 4H-SiC Using Bis-trimethylsilylmethane and Bis-cyclopentadienylvanadium Precursors

Abstract

The authors attempted to grow a semi-insulating 4H-SiC epitaxial layer by in situ vanadium doping. The homoepitaxial growth of the vanadium-doped 4H-SiC layer was performed by metallorganic chemical vapor deposition using the organosilicon precursor bis-trimethylsilylmethane (BTMSM, normalC7normalH20Si2 ) and the metallorganic precursor bis-cyclopentadienylvanadium (Verrocene, normalC10normalH10V ). The vanadium doping effect on the crystallinity of the epi layer was very destructive. Vanadium-doped epi layers grown under normal conditions had various crystal defects such as micropipes and polytype inclusions, but this crystallinity degradation was overcome by elevating the growth temperature. For measurement of the resistivity of the highly resistive vanadium-doped 4H-SiC epi layers, the authors used the on-resistance technique. Based on the measurements of the on-resistance of the Schottky barrier diode fabricated using the vanadium-doped epi layers, it was revealed that the residual donor concentration of the epi layers was decreased with increasing partial pressure of verrocene. The resistivity of the in situ vanadium-doped 4H-SiC epi layer was about 107–1012Ωcm .

Vanadium doping using VCl4 source during the chloro-carbon epitaxial growth of 4H-SiC

“…Similar triangular defects and degradation of the crystalline quality were observed previously in epitaxial growth of heavily V-doped 4H-SiC epilayers in Ref. [24]. However, no increase in the dislocation generation that would be expected when approaching the solubility limit has been detected in this work.…”

“…The bandgap levels of the vanadium acceptors have been previously reported to be located at 0.8-1.0 eV from the bottom of the conduction band in 4H-SiC [4][5][6]. The achieved resistivity in the SI epilayers was consistent with the previously reported vanadium-acceptor compensation mechanism in 4H-SiC [24]. No deep levels other than those related to V were observed in IRPL spectra, which also support the conclusion that V deep levels are mainly responsible for compensation.…”

“…This value is better than the best FWHM values of more than 22-23 arcsec achieved in V-doped epilayers produced by MOCVD using bis-trimethylsilylmethane and biscyclopentadienylvanadium precursors in Ref. [24]. Moreover, significantly higher growth rate of 6 mm/h was achieved in our work at similar growth temperatures of 1440-1450 1C, without surface defect generation.…”

“…Relatively few reports are available on epitaxial growth of SI SiC, which includes V-doped SiC epilayers [23,24] and SiC epilayers doped with Fe to achieve Fe-related deep levels [15]. V-doped 4H-SiC epilayers were achieved from a solid source in Ref.…”

“…[24], V-doped 4H-SiC epitaxial layers were grown by MOCVD at low growth rates of about 1 mm/h. While highly resistive epilayers were achieved, severe degradation in the surface morphology and crystalline quality were observed in the V-doped SI epilayers [24]. Additionally, no systematic study of the dependence of the morphology and the epilayer quality on the concentration of incorporated V was reported.…”