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Electrochemical and laser-induced etching processes were simultaneously used to synthesize the nanowires structure of porous
silicon (PS). Surface morphology and structural properties of nanostructured silicon were characterized by using scanning
electron microscopy (SEM) and atomic forces microscopy (AFM) images. Nanowires with dimensions of few n...
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... process of laser-induced etching is initiated to form the PS structure due to the availability of high density of the electron-hole pairs confined at the semiconductor Fig. 1 The electrochemical etching set-up Figure 4 shows uniform column walls and that the pore structures are grown deeper with thinner pore walls. This is attributed to the large number of the electron-holes generated within the PS columns resulting in future dissolution of the porous layer. ...
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Highly n-doped silicon nanowires (SiNWs) have been grown by a chemical vapor deposition process and have been investigated as possible electrodes for electrochemical capacitors (ECs) micro-devices. Their performances have been compared to existing literature on the field, which shows the use of SiNWs fabricated via different techniques, SiC coated...
Chemical modifications including Ag nanoparticle deposition have been performed on electrochemically formed mesoporous silicon (PS) to optimize confinement and templating of molecular systems within PS as well as to modify the electronic properties of both the host and the guest. A complete quenching of photoluminescence (PL) of PS along with a con...
Pulse laser deposition was used in this research by Nd:YAG laser with λ=1064 nm average frequency 6 Hz and pulls duration 10 nm) to deposit ZnO thin films with thickness 100 nm. From Atomic Force microscope of prepared samples show an decrease in average diameter with increase etching time. From FTIR spectra of porous silicon with constant current...
Porous silicon (PS) layers were fabricated on n-type crystalline silicon (c-Si) wafers of (100) and (111) orientations using photoelectrochemical etching (PECE) process at etching time of 20 min, current density of 60 mA/cm 2 , and fixed electrolyte solution HF:C 2 H 5 OH (1:4). Moreover, PS layers fabricated on p-type c-Si wafers of (100) and (111...
We investigate the photoluminescence (PL) behavior of the porous silicon nanowire (PSiNW) arrays synthesized via metal-assisted electroless etching method on the n-Si (100) substrate. Two PL bands with different origins dependent on the post-chemical treatments were detected. The red emission band, the peak position of which is insensitive to tempe...
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... The features of the surface have a significant impact on Si's properties. As a result, it is believed that the quantum confinement effects control how nanocrystalline luminescence works [20][21][22][23][24][25][26]. Silicon nanowires (SiNWs) or pyramid Si-based photodetectors are arrays of SiNWs that are aligned vertically on the planar substrate of the crystalline silicon wafer. ...
The effect of hydrofluoric (HF) acid concentration on the optoelectronic properties of porous silicon (PS) was investigated. The laser-assisted etching (LAE) method was used to prepare the PS samples. Etching parameters such as an etching period of 12 min and a current density of 20 mA cm−2 were relied upon. The crystallite size of the PS was investigated by XRD as well to provide an estimate of the degree of crystallinity of the etched samples. The XRD pattern exhibits significant (111) peaks at 28.4°. The FESEM investigation shows the roughness and hillocks on the entire surface which can be considered as a point to form small skeleton clusters that play an important role in the strong visible photoluminescence (PL). We can infer from our PL study that the PL peaks regarding the PS samples are related to S-band luminescence, corresponding to the blue–red emission 580–620 nm. A slight PL band position shifts toward shorter wavelengths, which could be explained by reductions in luminescent nanocrystal sizes with a porosity increase. Raman peak shifts and becomes asymmetrically broadened as the dimensions of c-Si are shrunk, as the HF concentration is increased, the Raman sharp peaks become more asymmetrical, and their peak locations shift to lower wavenumber in comparison with our reference bulk data. The analysis is performed on the electrical features of I–V characteristics, barrier height, and PS responsivity. The photosensitivity investigations reveal that responsivity is higher for PS sample prepared at 22% HF concentration. The resultant’s PS showed the best stability of the photocurrent, indicating that a high concentration can improve the stability of porous silicon optoelectrical characteristics. Under various HF concentrations, the quantum efficiency is assessed. The obtained results demonstrated rather unique results for the most efficient photodetector performance.
... To date various methods are reported for the fabrication of SiNWs, like chemical or physical vapor deposition, electron beam evaporation [10], electroless etching [11], vapor-liquid-solid growth [12], ion implantation technique [13], electrochemical etching technique [14], laser ablation [15], silver induced chemical etching (SICE) technique [16] etc. among various other techniques. A particular technique, chosen for the synthesis of Si-NWs onto Si substrate depends on availability, suitability, and also each technique has it's own pros and cons. ...
Determining the electron field emission (FE) turn-on field of the silicon nanowires(SiNWs) array can better adapt to the application of field-assisted photocathode. Here, we report the observations of FE from SiNWs grown on n-type Si(100) by utilizing silver induce chemical etching (SICE) approach. The growth of SiNWs is confirmed by XPS and XRD spectra and the optical band gaps, studied from the Kubelka-Munk function reveals the red shifting behavior. The grown SiNWs show an excellent FE property. The new proposed analytical framework enables one to understand the FE properties in better sense as compared to the conventional utilized framework, named as Fowler-Nordhiem (F-N) approach. It improves the analysis by introducing a new parameter i.e. boost-factor to take care of the FE data in totality unlike the traditional framework, where only currents were considered for higher electric fields. Moreover, it also addresses the ambiguity present in the previously used approach. A quantum mechanical model is adopted to explain the improved FE properties from these NWs by using the concept of tunneling probability. These results can enrich our knowledge on the FE of SiNWs and are highly related to the development of the next-generation of Si nano-electronic devices.
... The Schottky contacts (Pt/n-PSi) are determined based on PSi electron affinity and Pt work function. Given the electron affinity of the semiconductor and the nature of metal, the junction exhibits a Schottky behavior [14], where the charge carriers are mobilized unrestrained, into or outside the semiconductor [15]. In this case, minimum resistance is observed as the contact is traversed. ...
Despite several attempts to enhance the electrical and charge carrier transport characteristics of porous silicon (PSi), the requisite conditions for optimally synthesizing n-PSi with appealing optoelectronic properties are yet to be achieved. Therefore, this research explores the effect of the chemical ratio of precursor materials (HF:C 2 H 6 O:H 2 O 2) on the surface morphology, crystalline structure, and optical and electric properties of PSi. The PSi was produced by photoelectrochemical etching followed by anodization of the n-type Si under light illumination. The properties of the as-prepared PSi were studied by means of microscopic and spectroscopic techniques. The HF:C 2 H 6 O:H 2 O 2 chemical ratio was optimized at 2 : 1 : 1. A metal-semiconductor-metal (MSM) ultraviolet photo-detector (Pt/n-PSi/Pt) was fabricated, which exhibited high performances under UV light (365 nm) illumination. The photodetector was shown to be highly stable and reliable with a rapid rise time of 0.56 s at a bias voltage of +5 V. The MSM photodetector displayed responsivity (R p) of 9.17 A/m at 365 nm, which significantly exceeds the values reported for TiC/porous Si/Si in some contemporary research. The photodetector fabricated from n-PSi, synthesized at an optimum chemical ratio (2 : 1 : 1) exhibited the best photo-detection performance, possibly due to the high porosity and defect-free state of the n-PSi thin films.
... Indicated the low (weak QCE) and high (strong QCE) radiative recombination rate in PSi etched at 30 and 60 s, respectively. The observed increase in the PL peak intensity for PSi etched at 60, 90, and 120 s was due to the rise in the strong QCE-mediated radiative recombination rate (tinier nanocrystallites at longer etching time) [52]. Figure 3b4 illustrates the etching time-dependent peak emission wavelength and RMS roughness of PSi. ...
Charge carriers’ generation from zinc includes silicon quantum dots (ZnSiQDs) layer
sandwiched in-between porous silicon (PSi) and titania nanoparticles (TiO2NPs) layer-based solar cell is an efficient way to improve the cell’s performance. In this view, ZnSiQDs layer with various QDs sizes have been inserted, separating the PSi and TiO2NPs layers to achieve some graded bandgap quantum dot solar cells (GBQDSCs). In this process, ZnSiQDs of mean diameter 1.22 nm is first prepared via the top-down method. Next, ZnSiQDs have been re-grown using the bottom-up approach to get various mean diameters of 2.1, 2.7 and 7.4 nm. TiO2NPs of mean diameter in the range of 3.2 to 33.94 nm have been achieved via thermal annealing. The influence of different ZnSiQDs sizes
on the designed GBGQDSCs performance has been determined. The proposed cell attains a short circuit current of 40 mA/cm2 and an efficiency of 4.9%. It has been shown that the cell performance enhances by optimizing the energy levels alignment in the PSi, ZnSiQDs, TiO2NPs layers.
... The characteristics of the surface strongly affect the properties of Si. Therefore, the quantum confinement effects are considered to control the mechanism of the luminescence in nanocrystalline [7]. The porous silicon application as a sensor involves various sensor types like the optical sensor. ...
... The emission line width decreased, compared to what is observed in Fig. 6, producing a very sharp PL peak as a result of a hot etching solution, in a good agreement with ref. [65]. Most of the nanomaterials give broaden PL spectra due to a huge variety in their size distribution, however as the nanomaterial became more homogenous, its PL spectrum became sharper as mentioned in several previous works [32,66,67]. In addition, the exponential increase in the PL peak intensities using hot solution during the MACE process, as seen in Fig. 7, can be understood on the basis of Fig. 5a. ...
Silicon is the most widely used semiconductor material for electronics and energy related applications. Herein, different Si nanostructures with various shapes, sizes and morphologies are fabricated by a simple, low-cost and versatile metal‐assisted chemical etching (MACE) technique using Ag nanoparticles as a catalyst, deposited on Si surface. The influence of etching time, temperature and intrinsic properties of the silicon substrate (e.g., orientation, crystallinity) on the basic process are studied. Fast preparation of porous silicon (PSi) was achieved on Si 〈1 0 0〉 at room temperature after only 30 s of exposure to etching solution. Meanwhile increased etching time led to increase the pore diameter and a well-aligned SiNWs was obtained after 10 min. However, the exposure of Si 〈1 0 0〉 to the etching solution at 60 °C for only 2 min produced a homogenous and dense SiNWs layer. Additionally, the orientation of Si wafer was found to play a key role during the MACE process. Particularly, the MACE has no effect on Si 〈1 1 1〉 before 30 min whereas a zigzage PSi was formed. PSi nanostructures with straight and zigzag structures were successfully fabricated for the first time in addition to well-aligned, uniform and vertical Si nanowires (SiNWs) with smooth and polygonal shapes. The as-prepared Si nanostructures are characterized by various techniques including field emission-scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), UV–vis. and photoluminescence spectroscopy (PL). The optical properties of as-prepared Si nanostructures are enhanced and the reasons for this improvement and its correlation with the morphology difference are presented and discussed.
... The nanostructured silicon has been very useful in energy storage [12,13], biology, chemical sensors [14,15] and optoelectronics [16,17]. Many methods have been developed to produce silicon nanostructures, such as electrochemical etching [18,19]; vapourliquid-solid growth (VLS) [20,21] and MACE [22][23][24]. ...
Silicon nanowires (SiNWs), with different ratios, have been elaborated by metal assisted chemical etching (MACE) on P3HT:SiNWs blends, deposited onto PET substrate. X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM) and hotoluminescence (PL) measurements have been used to control the structural, morphological and optical properties of the investigated structure. The best concentration chosen is followed by an annealing treatment. Our results prove that the optimal structure is obtained with the nanocomposite P3HT:SiNWs (1:1). The moderate annealing temperature, around 90°C, is most appropriate. A correlation between XRD, AFM and PL measurements can explain the decrease of charge transfer and the coupled of SiNWs with increasing concentration. Our results can improve the possibility to integrate those kinds of structures as an active layer in the photovoltaic applications.
... As can be seen, the Ag/PS prepared for 30 min has higher reflectivity value compared to the other samples. The reduction of the reflectivity is due to the enhanced scattering and light absorption in the porous and bulk interfaces [20,21] which is an important parameter to enhance the photoconversion process for some devices. Moreover, due to the different pore sizes (Fig. 1), some silver particles (Fig. 1(c)) and others decorate the PS surface ( Fig. 1(a) and (b)). ...
Porous silicon (PS) is a candidate for silicon-based optoelectronic applications. This paper presents the effect of etching time on the properties of PS deposited by a nano-thin film of a silver layer (10 nm Ag/PS) using radio frequency (RF)-sputtering technique at room temperature (RT). The PS was prepared by electrochemical etching (ECE) method for n-type (111) Si in an electrolyte solution containing hydrofluoric acid (HF) and ethanol (C 2 H 6 O) at a volume ratio of 1:4 with a direct current of 10 mA for different etching duration (30, 45, and 60 min). Structural, surface, and optical characterizations of the samples were carried out by using field emission scanning electron microscopy (FESEM), energy dispersive X-rays (EDX), X-ray diffraction (XRD), UV–Vis spectrophotometer, and photoluminescence (PL) spectroscopy. The results show that the sample prepared for 30 min demonstrated enhancement in the PL and reflectivity spectra compared to other samples which indicate a higher etching rate and a thinner wall between the pores on the surface over a larger exposed area was obtained.
... Commonly, the wet etching technique use DCPEC in HF acid based electrolytes. However recently, there are works such as [1,2,5,6] that implement the iPEC technique. The idea to integrate the iPEC technique is to rest and pause the current temporarily. ...
... Therefore, the setting of T on and T off must be in an appropriate ratio for a better formation of the porous structure as suggested in [1]. On the other hand, Naderi et al. claimed that the application of delay time in the iPEC technique can enhance the etching rate and may result in a uniform and deeper pore as it combined electroless and electrochemical etching [5,6] for the iPEC etching technique. Figure 4 shows the 2Θ-scan patterns of the sample etched due to different etching techniques. ...
... According to Nakamura et al. [10], there are several output parameters that need to be considered for measuring the performance of solar cell, which is maximum power (P max ), fill-factor (FF), short-circuit current (I sc ), and open-circuit voltage (V oc ). According to Ramizy et al. [11] the porous silicon has an effective feature that can improve the solar cell performance. Ramizy et al. [9] obtained the porous structure surfaces that contains discrete pores and short-branched pores at the top surfaces while smaller pore size and random pores at the bottom surfaces of the solar cell. ...
