On Photoelectrical Properties of 6H-SiC Bulk Crystals PVT-Grown on 6H- and 4H-SiC Substrates

Abstract:

Free carrier lifetimes and diffusion coefficients were determined in 6H-SiC bulk crystals grown by PVT on 6H-and 4H-SiC seeds varying the temperature from 300 K to 650 K and at excess carrier densities ΔN₀ from 10¹⁷ cm^-3 to 10¹⁹ cm^-3. Carrier generation was achieved by using a single or two-photon absorption of picosecond pulses at 351 and 532 nm, respectively. Fast and slow recombination transients revealed the decay time of free carriers and the presence of deep acceptor traps. The thermal trap activation energy E_a = 0.33 eV was determined in the 6H/4H sample and ascribed to the boron, while the presence of deeper traps is suggested in the 6H/6H sample. At room temperature and reaching conditions of trap saturation regime (ΔN₀ 10¹⁹ cm³), both crystals revealed the bipolar diffusion coefficient D_a 4 cm²/s. For comparison, we also determined the photoelectrical parameters in commercial 6H-SiC crystals grown by the Lely and PVT techniques.

• Periodical: Materials Science Forum (Volumes 778-780)
• Pages: 305-308
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.778-780.305
• Online since: February 2014
• Authors: Gediminas Liaugaudas*, Kęstutis Jarašiūnas, Nikolaos Tsavdaris, Eirini Sarigiannidou, Didier Chaussende
• Keywords: Bulk 6H-SiC, Carrier Lifetime, Diffusion Coefficient, Pump-Probe

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DOI: 10.1002/piuz.19760070417