Graphene nanoflakes and carbon nanotubes on porous silicon layers by spin coating, for possible applications in optoelectronics

Garzon-Roman, A.; Cuate-Gomez, D.H.

doi:10.1016/j.sna.2019.04.013

Cited by 10 publications

(3 citation statements)

References 39 publications

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“…One can note that SiNWs fabrication with good uniformity/reproducibility are a MACE feature [4,34]. It is worth noting that the observed rectifying behaviour of these SiNWs is similarly shown in the literature for porous silicon [42,[46][47][48]. Importantly, the nonlinear I-V characteristics and the rectifying event are mainly controlled by the SiNW layers and ascribed to Ag/SiNWs:p-Si since the Si/Al interface was proved to be ohmic [47,48].…”

Section: I-v Measurementssupporting

confidence: 64%

Elucidating the Effect of Etching Time Key-Parameter toward Optically and Electrically-Active Silicon Nanowires

et al. 2020

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In this work, vertically aligned silicon nanowires (SiNWs) with relatively high crystallinity have been fabricated through a facile, reliable, and cost-effective metal assisted chemical etching method. After introducing an itemized elucidation of the fabrication process, the effect of varying etching time on morphological, structural, optical, and electrical properties of SiNWs was analysed. The NWs length increased with increasing etching time, whereas the wires filling ratio decreased. The broadband photoluminescence (PL) emission was originated from self-generated silicon nanocrystallites (SiNCs) and their size were derived through an analytical model. FTIR spectroscopy confirms that the PL deterioration for extended time is owing to the restriction of excitation volume and therefore reduction of effective light-emitting crystallites. These SiNWs are very effective in reducing the reflectance to 9-15% in comparison with Si wafer. I-V characteristics revealed that the rectifying behaviour and the diode parameters calculated from conventional thermionic emission and Cheung's model depend on the geometry of SiNWs. We deduce that judicious control of etching time or otherwise SiNWs' length is the key to ensure better optical and electrical properties of SiNWs. Our findings demonstrate that shorter SiNWs are much more optically and electrically active which is auspicious for the use in optoelectronic devices and solar cells applications.Nanomaterials 2020, 10, 404 2 of 18 time-consuming and therefore hindered their applications for commercialized products. In contrast, an effective and promising synthetic method namely metal assisted chemical etching (MACE) has been proposed [2,4,[18][19][20]. This technique is simple, rapid, low cost, and suitable for both industrial and laboratory scales. Moreover, MACE allows to obtain high crystalline SiNWs quality, as well as an easy control of the different parameters including orientation, doping type, length, and diameter.The MACE method basically consists of two procedures, the formation of metal catalysts and the subsequent etching process which can be implemented either in a single step (1-MACE) [10,21] or in two steps (2-MACE) [17-20]. Moreover, the formation method, etching time, etching temperature, metal deposition time, and lastly the etchants' concentrations have a crucial influence on the morphology of SiNWs [2,5,17]. Ghosh et al. reported that SiNWs grown by MACE are usually covered with silicon nanocrystals due to the side wall etching and which are the origin of quantum confinement (QC) effects owing to their small dimensions [20]. Recently, several research groups have succeeded in the synthesis of optically-active SiNWs exhibiting a significant PL emission and a very low reflectance [3,4,17]. On the other hand, Qi et al. have demonstrated the fabrication of electrically-active SiNWs through heavily doped SiNWs with rough surface where a high Schottky barrier exists at the interface of SiNWs and the metal [22]. Nevertheless, further investigation is required t...

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Section: I-v Measurementssupporting

confidence: 64%

Elucidating the Effect of Etching Time Key-Parameter toward Optically and Electrically-Active Silicon Nanowires

et al. 2020

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“…Since some textiles may be incompatible with particular solvents, a self-standing sensor can be made on a different substrate and then attached to the fabric in the second step. These methods include dip-coating ( Figure 3 a—repetitive immersion of the substrate into the CNT dispersion) [ 90 , 91 , 92 , 93 , 94 ], spin-coating ( Figure 3 b—deposition of the CNT dispersion onto a rotating substrate) [ 95 , 96 , 97 ], and spray-coating ( Figure 3 c—use of compressed gas to coat the substrate with CNT aerosol) [ 98 ] (both spinning and spraying even out the thickness of the CNT coating on the substrate). To achieve the same effect, one can also use vacuum filtration [ 99 , 100 , 101 ].…”

Section: Formation Of Wearable Sensors From Cntsmentioning

confidence: 99%

Carbon Nanotube Wearable Sensors for Health Diagnostics

Rdest

Janas

2021

Sensors

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This perspective article highlights a recent surge of interest in the application of textiles containing carbon nanotube (CNT) sensors for human health monitoring. Modern life puts more and more pressure on humans, which translates into an increased number of various health disorders. Unfortunately, this effect either decreases the quality of life or shortens it prematurely. A possible solution to this problem is to employ sensors to monitor various body functions and indicate an upcoming disease likelihood at its early stage. A broad spectrum of materials is currently under investigation for this purpose, some of which already entered the market. One of the most promising materials in this field are CNTs. They are flexible and of high electrical conductivity, which can be modulated upon several forms of stimulation. The article begins with an illustration of techniques for how wearable sensors can be built from them. Then, their application potential for tracking various health parameters is presented. Finally, the article ends with a summary of this field’s progress and a vision of the key directions to domesticate this concept.

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“…Porous organic polymers (POPs) [ 1 ] are an emerging class of multifunctional porous materials, which are constructed from covalently bonded organic moieties. Because of their unique properties derived from their tunable porous structures and the multiple functional groups, which can be included in their backbones, POPs have been actively investigated for multiple applications including gas storage/separation, [ 2,3 ] catalysis, [ 4–6 ] optoelectronics, [ 7,8 ] sensing, [ 9–11 ] energy storage, and conversion. [ 12,13 ] Aside from their high specific surface areas, they furthermore show excellent chemical stability, light‐weight and a versatile chemistry for modification and functionalization.…”

Section: Introductionmentioning

confidence: 99%

Macroscale Conjugated Microporous Polymers: Controlling Versatile Functionalities Over Several Dimensions

et al. 2022

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covalently bonded organic moieties. Because of their unique properties derived from their tunable porous structures and the multiple functional groups, which can be included in their backbones, POPs have been actively investigated for multiple applications including gas storage/separation, [2,3] catalysis, [4][5][6] optoelectronics, [7,8] sensing, [9][10][11] energy storage, and conversion. [12,13] Aside from their high specific surface areas, they furthermore show excellent chemical stability, light-weight and a versatile chemistry for modification and functionalization. POPs can be further classified into two categories based on their crystallinity. Crystalline POPs are usually summarized under the name covalent organic frameworks [14][15][16] (COFs). Amorphous POPs are further divided, based on their structure or construction principles into hyper-crosslinked polymers [17,18] (HCPs), polymers of intrinsic microporosity [19,20] (PIMs), porous aromatic frameworks [21,22] (PAFs), and others. Recent research has seen increasing interest on amorphous POPs, especially when their skeleton is π-conjugated. In these highly porous networks, π-conjugation is superimposed with meso-/microporosities, i.e., electron transport in the polymer backbone is accompanied by mass transport in the porous system, which enable many intriguing properties and applications, e.g., in energy storage and conversion, [23,24] or optoelectronics. [25,26] As such, the importance of π-conjugation in porous polymer networks has defined another emerging functional POP class-the conjugated microporous polymers (CMPs). As mentioned, such CMPs [27] are a unique class of POPs exhibiting extended π-conjugated structures and permanent nanopores (Table S1). Earlier, McKeown et al. [28] discussed an important concept of preparing robust nanoporous materials by the covalent binding of planar molecules via a rigid spirocyclic linker. In 2007, Cooper et al. [29] reported a highly cross-linked, microporous poly(arylene ethynylene)s network, thus the first microporous polymer network with distinct π-conjugation and introduced the term "conjugated microporous polymer (CMP)" for this class of materials. Since their discovery, CMPs chemistry has intrigued scientists across the globe and been promoted rapidly, resulting in a strong growth in publications over the last decade. For instance, Thomas et al. [30] reported a spirobifluorene-type CMP with stable interface and application potential in organic light emitting diodes Since discovered in 2007, conjugated microporous polymers (CMPs) have been developed for numerous applications including gas adsorption, sensing, organic and photoredox catalysis, energy storage, etc. While featuring abundant micropores, the structural rigidity derived from CMPs' stable π-conjugated skeleton leads to insolubility and thus poor processability, which severely limits their applicability, e.g., in CMP-based devices. Hence, the development of CMPs whose structure can not only be controlled on the micro-but also on the macroscale have...

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Graphene nanoflakes and carbon nanotubes on porous silicon layers by spin coating, for possible applications in optoelectronics

Cited by 10 publications

References 39 publications

Elucidating the Effect of Etching Time Key-Parameter toward Optically and Electrically-Active Silicon Nanowires

Elucidating the Effect of Etching Time Key-Parameter toward Optically and Electrically-Active Silicon Nanowires

Carbon Nanotube Wearable Sensors for Health Diagnostics

Macroscale Conjugated Microporous Polymers: Controlling Versatile Functionalities Over Several Dimensions

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