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Your search keyword '"Magginetti, David J."' showing total 8 results
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8 results on '"Magginetti, David J."'

1. Heterogeneous Optoelectronic Characteristics of Si Micropillar Arrays Fabricated by Metal-Assisted Chemical Etching

Author

Qian, Yang, Magginetti, David J., Jeon, Seokmin, Yoon, Yohan, Olsen, Tony L., Wang, Maoji, Gerton, Jordan M., and Yoon, Heayoung P.

Subjects
Physics - Applied Physics, Condensed Matter - Materials Science, Physics - Optics
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/SiOx shell on crystalline pillar cores introduced by local electrochemical reactions. In this paper, we report the distinct optoelectronic characteristics of the porous Si/SiOx 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 (about 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 (about 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 SiOx in hydrofluoric acid. These distinct optoelectronic characteristics of the Si/SiOx shell can be beneficial for various sensor architectures., Comment: 4 figures, 1 table

Published
2020
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6. Resolving surface potential variation in Ge/MoS2 heterostructures with Kelvin probe force microscopy.

Author

Woo, Sanguk, Yoo, Jinkyoung, Magginetti, David J., Bilgin, Ismail, Kar, Swastik, Yoon, Heayoung P., and Yoon, Yohan

Subjects
KELVIN probe force microscopy, SURFACE potential, HETEROSTRUCTURES, CHEMICAL vapor deposition, ELECTRON work function, NUCLEAR forces (Physics)
Abstract

In this work, we employ an atomic force microscopy-based technique, Kelvin probe force microscopy, to analyze heterogeneities of four different 2D/3D Ge/MoS2 heterostructures with Ge chemical vapor deposition (CVD) time. High-contrast spatially resolved contact potential difference (CPD) maps reveal the evolution of the samples by Ge deposition. The CPD map in an as-prepared sample does not display any heterogeneity, but CPD contrasts along the grain boundaries are obviously noticed as Ge is deposited on MoS2. With a sufficiently long Ge CVD deposition time, strong grain-to-grain CPD variations over the 2D/3D heterostructures are observed. The results show the variations of the work function from grain to grain that are attributed to the strain induced by the Ge island formation on the cracked MoS2 initiated by sulfur vacancies. [ABSTRACT FROM AUTHOR]

Published
2021
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