Effective carrier lifetime in ultrashort pulse laser hyperdoped silicon: sulfur concentration dependence and practical limitations
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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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Date
2024-12
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Language
en
Pages
8
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Physica Status Solidi (A) Applications and Materials Science, Volume 221, issue 24
Abstract
Charge carrier lifetime is a crucial material parameter in optoelectronic devices and knowing the dominant recombination channels points the way for improvements. The effective carrier lifetime τ eff of surface-passivated hyperdoped (hSi) and nonhyperdoped “black” (bSi) silicon by quasi-steady-state photoconductance decay (QSSPC) measurements and its evolution upon controlled wet-chemical etching are studied. Sample preparation involves the irradiation of Si by numerous ultrashort laser pulses either in SF 6 for hSi or ambient atmosphere for bSi. Findings suggest that the hSi is composed of a double layer: 1) an amorphous resolidified top layer with about 92% of the total incorporated sulfur that accounts for the sub-bandgap absorptance and 2) a crystalline layer underneath in which sulfur concentration tails off toward the Si substrate. The effective lifetime is deconstructed by a 1D simulation to quantify the impact of the local lifetime of the defect-rich top layer, τ top. It is found that by the QSSPC method, a maximum τ top for 1) can be estimated. For 2), τ top between 2 and 8 ns is estimated. The bSi sample shows a faster lifetime recovery upon etching which suggests that in hSi samples purely laser-induced defects are not limiting the carrier lifetime compared to sulfur-related defects.Description
Keywords
effective carrier lifetime, silicon, simulation, wet-chemical etching, hyperdoping
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Citation
Schäfer, S, Liu, X, Mc Kearney, P, Paulus, S, Radfar, B, Vähänissi, V, Savin, H & Kontermann, S 2024, ' Effective carrier lifetime in ultrashort pulse laser hyperdoped silicon: sulfur concentration dependence and practical limitations ', Physica Status Solidi (A) Applications and Materials Science, vol. 221, no. 24, 2400132 . https://doi.org/10.1002/pssa.202400132