Heterogeneous optoelectronic characteristics of Si micropillar arrays fabricated by metal-assisted chemical etching

Abstract Recent progress achieved in metal-assisted chemical etching (MACE) has enabled the production of high-quality micropillar arrays for various optoelectronic applications. Si micropillars produced by MACE often show a porous Si/SiO x shell on crystalline pillar cores introduced by local elect...

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Autores principales: Yang Qian, David J. Magginetti, Seokmin Jeon, Yohan Yoon, Tony L. Olsen, Maoji Wang, Jordan M. Gerton, Heayoung P. Yoon
Formato: article
Lenguaje:EN
Publicado: Nature Portfolio 2020
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Acceso en línea:https://doaj.org/article/2114907b527a44e582b3d123598fc2fd
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Sumario:Abstract Recent progress achieved in metal-assisted chemical etching (MACE) has enabled the production of high-quality micropillar arrays for various optoelectronic applications. Si micropillars produced by MACE often show a porous Si/SiO x shell on crystalline pillar cores introduced by local electrochemical reactions. In this paper, we report the distinct optoelectronic characteristics of the porous Si/SiO x shell correlated to their chemical compositions. Local photoluminescent (PL) images obtained with an immersion oil objective lens in confocal microscopy show a red emission peak (≈ 650 nm) along the perimeter of the pillars that is threefold stronger compared to their center. On the basis of our analysis, we find an unexpected PL increase (≈ 540 nm) at the oil/shell interface. We suggest that both PL enhancements are mainly attributed to the porous structures, a similar behavior observed in previous MACE studies. Surface potential maps simultaneously recorded with topography reveal a significantly high surface potential on the sidewalls of MACE-synthesized pillars (+ 0.5 V), which is restored to the level of planar Si control (− 0.5 V) after removing SiO x in hydrofluoric acid. These distinct optoelectronic characteristics of the Si/SiO x shell can be beneficial for various sensor architectures.