Non-Equilibrium Carrier Diffusion and Recombination in Semi-Insulating PVT Grown Bulk 6H-SiC Crystals

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We applied a non-degenerate four wave mixing (FWM) technique to investigate carrier generation, diffusion and recombination processes in PVT-grown semi-insulating wafers of 6H-SiC at 300 K. The resistivity of samples, cut from different places of a boule as well as from different boules, varied in range from a few ⋅cm up to 1010 ⋅cm. Interband excitation (at 355 nm) and below bandgap excitation (at 532 nm) allowed to study dynamics of the bipolar plasma and the contribution of deep levels to carrier generation and recombination. The nonequilibrium carrier lifetime was shorter in the samples of higher resistivity, in accordance with the increasing density of deep levels. The bipolar plasma diffusion in high-resistivity samples (~109 ⋅cm) provided the value of the diffusion coefficient D = 4.4 cm2/s and hole mobility μh = (88 ± 6) cm2/Vs.

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Periodical:

Materials Science Forum (Volumes 527-529)

Edited by:

Robert P. Devaty, David J. Larkin and Stephen E. Saddow

Pages:

469-472

Citation:

K. Neimontas et al., "Non-Equilibrium Carrier Diffusion and Recombination in Semi-Insulating PVT Grown Bulk 6H-SiC Crystals", Materials Science Forum, Vols. 527-529, pp. 469-472, 2006

Online since:

October 2006

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[1] [10] ρ=1010 Ωcm γ=2. 0 γ=1. 1 γ=2. 0 ∆t=500 ps γ=2. 4 Excitation intensity (mJ/cm.

[2] ) Diffraction efficiency (a. u. ) b) Fig. 3. Dependences of diffraction efficiency on excitation intensity at 355 nm in 6H-SiC samples with different resistivity. The grating period is 18. 7 µm. For slope value γ, see the text.