Abstract
In the current research, a porous silicon/zinc oxide (PSi/ZnO) nanocomposite produced by a combination of metal-assisted chemical etching (MACE) and atomic layer deposition (ALD) methods is presented. The applicability of the composite for biophotonics (optical biosensing) was investigated. To characterize the structural and optical properties of the produced PSi/ZnO nanocomposites, several studies were performed: scanning and transmission electron microscopy (SEM/TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), diffuse reflectance, and photoluminescence (PL). It was found that the ALD ZnO layer fully covers the PSi, and it possesses a polycrystalline wurtzite structure. The effect of the number of ALD cycles and the type of Si doping on the optical properties of nanocomposites was determined. PL measurements showed a “shoulder-shape” emission in the visible range. The mechanisms of the observed PL were discussed. It was demonstrated that the improved PL performance of the PSi/ZnO nanocomposites could be used for implementation in optical biosensor applications. Furthermore, the produced PSi/ZnO nanocomposite was tested for optical/PL biosensing towards mycotoxins (Aflatoxin B1) detection, confirming the applicability of the nanocomposites.
Highlights
It is well known that porous silicon (PSi), due to its high surface-to-volume ratio and superior photoluminescence (PL) properties, is an attractive material for opticalsensing applications [1,2].the instability of PSi properties in solutions due to the degradation process needs to be solved in order to obtain a stable response and repeatable results [3]
It was demonstrated that the improved PL performance of the porous silicon/zinc oxide (PSi/Zinc oxide (ZnO)) nanocomposites could be used for implementation in optical biosensor applications
We report on the investigation of the structural and optical properties of PSi/ZnO
Summary
It is well known that porous silicon (PSi), due to its high surface-to-volume ratio and superior photoluminescence (PL) properties, is an attractive material for optical (bio)sensing applications [1,2].the instability of PSi properties in solutions due to the degradation process needs to be solved in order to obtain a stable response and repeatable results [3]. Zinc oxide (ZnO) is one of the possible candidates that could be combined with PSi because of its excellent optical properties (e.g., stable PL signal in the wide optical range), and which may be used in biophotonic applications, biosensors [9,10,11]. Nanocomposites based on PSi/ZnO have attracted more and more attention over the years [12,13,14,15,16]. The underlying reasons behind their popularity are attributed to the synergistic effects on physical and, optical properties of the PSi/ZnO, which are derived from the combination of individual features of both semiconductors [17,18,19,20,21,22]. The improved catalytic activity, high charge carrier mobility and relatively high biocompatibility make the PSi/ZnO nanocomposite a perfect material for a Materials 2020, 13, 1987; doi:10.3390/ma13081987 www.mdpi.com/journal/materials
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