PL Data Research Articles

Structural and LuminescentProperties of Dy(III) DopedCa0.5Bi3P2O10 Nanophosphors for Solid-State Lighting& Latent Fingerprinting Applications.

Anefficient urea-assisted SC (solution-combustion)approach was used to synthesize a novel series ofdoped Ca0.5Bi3P2O10: xDy3+ nanophosphors (0.01-0.1mol). The powdered materials were thoroughly investigated using structural and optical measures. 'Rietveld refinement'investigations found that the produced nanophosphorformed a triclinic system with the P -1 triclinic space group. An EDS (energy-dispersive spectral)study was conducted to determine the corresponding proportions of constituentelements of doped nanophosphors. The TEM (transmission electron microscopy)revealed aggregated particles with a standard size onthe nanoscale. The PLE (Photoluminescence excitation)spectrum indicates that the indicated phosphors can be stimulated by NUV (near ultraviolet)illumination sources. The Dy3+-ions undergo transitions from (4F9/2 → 6H15/2 & 4F9/2 → 6H13/2) were recognized as (PL) spectra with an excitation of 353nm revealed the presence of blue-yellow bands at 481, and 577nm, correspondingly. Further, PL data was used to determine photometric metrics such as CCT (correlated color-temperature), CC (chromaticity-coordinates (x &y)), and CP (color-purity (%)), supporting their use in solid-state lighting and latent fingerprinting applications.

Phase identification and photophysical characteristics of vanadate-based nanophosphors for lighting and latent fingerprinting applications

Monoclinic structure-based Er3+-activated Ba2BiV3O11 nanophosphors have been developed via an easy and cost-efficacious urea-aided solution combustion (SC) procedure. Various spectroscopic and structural investigations thoroughly examine the produced powders. The crystal structure has been resolved by employing a combination of X-ray diffraction (XRD) and the Rietveld refinement practice. The developed powdered nanosamples are crystallized in a monoclinic crystal system with P21/a space group. Further, to evaluate the composition of elements and their relative distribution, energy dispersive X-ray (EDAX) analysis was performed. The band gap values for the host matrix and the optimal nanophosphors were measured using a DR spectrophotometer; the obtained values were 3.47 eV and 3.40 eV, respectively. The strongest excitation peak at 381 nm is closely-matched with the characteristic wavelength of commercialized near ultraviolet (NUV) based LEDs. The characteristic emission spectra of Ba2Bi1-xErxV3O11 (x = 0.01–0.1) phosphors show the strongest emission at 553 nm (4S3/2 → 4I15/2). Additionally, photometric parameters such as quantum efficiency (86 %), color coordinates (x = 0.2568 and y = 0.4551), and correlated color temperature (CCT = 7722 K) are obtained from PL data and are strongly advised for use in wLEDs, color displays, imaging, lighting, and latent fingerprint applications.

Low concentration Sm3+ ions loaded zinc sodium borate glasses for solid state lighting devices

Herein, zinc sodium borate glasses containing samarium ions were fabricated using the traditional melt-quenching approach and explored using several spectroscopic and structural methods. The XRD data corroborated the host glass specimen's non-crystalline nature. Scanning electron microscopy and the energy dispersive X-ray spectroscopy method were utilized to study the morphological and homogenous attributes. The UV–Vis–NIR wavelengths of absorption showed a total of seventeen distinct Sm3+ ion peaks. The three transitions 4G5/2 → 6H9/2, 6H7/2, and 6H5/2 are evident in the PL data at wavelengths of 644, 597, and 561 nm, respectively, in the red, reddish-orange, and greenish-yellow zones. The luminescence intensity of the investigated glass specimens increases up to 0.4 mol% Sm3+ ion content thereafter reducing because of the non-radiative transfer of energy. The estimated JO intensity parameters exhibit a trend of Ω2>Ω4>Ω6. The trend of the assessed radiative parameters also demonstrated that they are sensitive to changes in the glass network. The Futchbauer-Ladenburgh theory was used to compute the emission cross-section of various transitions utilizing the radiative parameters. The 1931 CIE chromaticity coordinates assessments corroborate the reddish-orange luminescence from the fabricated glasses. The outcomes have proven that obtained BNZSmx glasses doped with low concentrations of trivalent samarium ions are well suited for reddish-orange solid-state lighting systems.

Efficient and Traceable Tamoxifen Delivery to Breast Cancer Cells Using Folic Acid‐Decorated and PEGylated Graphene Quantum Dots

AbstractGraphene quantum dots (GQDs) possess potential properties for the targeted transport and tracking of anticancer medication to tumor cells. For this purpose, the synthesized GQDs were decorated with folic acid (FA) and methoxy polyethylene glycol (mPEG2000), and finally loaded with tamoxifen (TMX) drug. The synthesized nano‐drug was characterized using FTIR, XRD, UV‐Vis, PL, HRTEM, FESEM, and DLS analytical devices. Based on the obtained data, the average hydrodynamic diameter of particles dissolved in water was 294.7 nm and the size of dehydrated particles was between 53 and 210 nm. PL data showed that prepared nanoparticles have an emission wavelength of 438 nm, which is in the blue fluorescent wavelength range, thus making these nanoparticles suitable for cell imaging. The encapsulation efficiency and loading percentage of tamoxifen in nanoparticles were calculated at about 52.5 % and 30 %, respectively, and cumulative drug release reached 89 % within 42 hours. The cytotoxicity effects of nanoparticles were investigated. According to IC50 results, the targeted mPEG‐GQDs‐FA/TMX (TMX‐FPGs) nano‐drug was more toxic than free TMX on MCF‐7 cells and had reduced side effects on healthy HDF cells. TMX‐FPGs induced apoptosis cell death, significantly. The confocal imaging experiments showed that TMX‐FPGs are appropriate for monitoring and targeting MCF‐7 cells.

Effect of Complexation with Closo-Decaborate Anion on Photophysical Properties of Copolyfluorenes Containing Dicyanophenanthrene Units in the Main Chain

The functionalization of copolyfluorenes containing dicyanophenanthrene units by closo-decaborate anion is described. Target copolyfluorenes were analyzed using SEM, UV-vis, luminescence, NMR, and Fourier-transform infrared (FTIR) spectroscopy. The effect of complexation with the closo-decaborate anion on the photophysical properties was studied both experimentally and theoretically. The PL data indicate an efficient charge transfer from fluorene to the dicyanophenanthrene units coordinated to the closo-decaborate. The coordination of closo-decaborate clusters to the nitrile groups of copolyfluorenes provides an important route to new materials for sensors and light-emitting devices while, at the same time, serving as a platform for further study of the nature of boron clusters.

Novel and facile strategy for immobilization of Ag3PW12 crystals on graphitic carbon nitride (g-C3-N4) sheets, a superior photocatalyst for decomposition of organic waste

The high electron-holes recombination rate in pure graphitic carbon nitride (C3–N4) restrict their photocatalytic efficiency. In this research work, we successfully immobilized Ag3PW12O40 a polyoxometalate-base crystal on graphitic carbon nitride 2D sheet through physical grinding method to prevent charges recombination on the surface. Both the materials were prepared separately and then grinded after mixing, to get C3–N4@Ag3PW12 heterojunction. The prepared C3–N4@Ag3PW12 composites were tested with different characterization techniques to confirm its structural integrity and successful fabrication of heterojunction. The composite catalyst showed expansion in UV light absorbance where it promotes from 406 nm to 454 nm for pure C3–N4 and composite C3–N4@Ag3PW12-30 % respectively. The composite showed better electron-holes separation, confirmed from its electrochemical performance such as TPC (total photocurrent) and PL data. The prepared catalysts were tested for the degradation of two types of organic dyes such as methylene blue and Rhodamine B under photoirradiation. The C3–N4@Ag3PW12-30 % composite photocatalyst showed efficient photocatalytic activity and removed 99 % methylene blue in 75 min while removed 99.4 % Rhodamine B in 60 min while the pure Ag3PW12 and C3–N4 could only remove 26.3 % and 37.7 % methylen blue and 43.54 % and 53.38 % rhodamin B respectively, in the same conditions. The results show that, the Ag3PW12 crystals deposition on C3–N4 2D sheets is a preferred approach to enhance the catalytic performance of C3–N4 2D sheet.

The barriers for electron and hole injection from Si substrate into the RF magnetron-deposited In2O3 : Er films

The In2O3 : Er films were deposited on Si substrates by the RF magnetron sputtering technique. For the Si substrates of both n- and p-type the current through the MOS-structure (Si/In2O3 : Er/In-contact) was described by the thermionic emission of the main currents over the barrier, with the correction of the applied voltage into the partial voltage drop in silicon. By the temperature dependence measurements of the forward currents at small under-barrier biases the barriers for the current injection from Si into the films were found equal to the 0.14 eV and 0.3 eV for the electrons and holes accordingly. The obtained small barrier for the holes is described by the presence of the defect state density. It tails from the valence band maximum into the In2O3 : Er band gap and provides there the conduction channel for holes. The defect state density in the In2O3 : Er band gap is proved by the PL data in the respective energy range 1.55–3 eV. The band analysis for the hetero-structure Si/In2O3 : Er is performed. It gives the energy gap between the electrons in the In2O3 : Er conduction band and the holes in the band gap channel equal to the 1.56 eV.

N-UV triggered green emitting Er3+ doped Zirconia: A bifunctional material for solid-state lighting and optical thermometry

In the current piece of work, we have synthesized the Er3+-activated ZrO2 and illustrated the bifunctional utility of this material for solid-state lighting and non-contact optical thermometry. The synthesized samples were characterized by XRD, XPS, and PL techniques for their structural, surface, and luminescence studies. Under the excitation of 377 nm, characteristic green emission corresponding to intra 4f-4f transitions of Er3+ is obtained. The concentration quenching effect was observed beyond 1.2 mol % concentration of doping. Using Dexter's theory, it was revealed that dipole-quadrupole interactions are predominantly responsible for concentration quenching. The Photometric study was performed using the PL data. For the most intense phosphor, a highly pure green color (color purity ∼ 97.6%) and CCT ∼ 5375 K is observed. Furthermore, the temperature-sensing capability of the most intense sample has also been explored by triggering the synthesized phosphor by n-UV light. The temperature sensing performance is checked by measuring variations in the fluorescence intensity ratio (FIR) of the thermally coupled levels of Er3+ with temperature. The synthesized phosphor gives high relative sensitivity (1.19% K−1 at 303 K)) and absolute sensitivity (11.39 × 10−4 at 603 K)) values. These results suggest that n-UV-triggered Er3+ doped ZrO2 can be a promising bifunctional material for applications in solid-state lighting and non-contact optical thermometry.

Robust white light emission of UV pumped SrCeO3: xSm3+ perovskites for wLEDs

Abstract Single phased white light emitting phosphors are more ideal for fabricating white LEDs due to higher stability and color reproducibility. Herein, we report a new white light emitting phosphor, SrCeO3: xSm3+ (x = 1 wt%, 2 wt%, 3 wt%) from a blue light emitting phosphor, SrCeO3 using an efficient, low energy consuming fuel excess gel combustion technique. From the XRD crystallographic investigation, all the synthesised samples have orthorhombic structure with space group Pnma. A broad absorption band in the UV–visible spectra around 350 nm occurs due to the efficient energy transfer from Ce4+ to Sm3+ ion. PL spectra analysis at UV excitations 280 nm and 406 nm, consist of 4f-Sm3+ transitions 4G5/2-6H5/2, 4G5/2-6H7/2, 4G5/2-6H9/2 and charge transfer band from O2− to Ce4+. The energy transfer between activator ions occurs through dipole–dipole interaction, owing to concentration quenching after 2 wt% Sm3+ and the optimised dopant concentration was 2 wt%. SrCe0.98Sm0.02O3 showed mixed blue-yellow-orange-red emission, owing near white light under both excitations. PL data were utilised to find the color parameters and found high color rendering index (CRI ∼ 84) for optimised sample at 406 nm excitation. SEM analysis reveals that the optimised sample exhibit dense ensembled morphology with well-defined grain boundaries and uniformity with average grain size ∼1.24 μm. Further, the elemental composition was confirmed using EDS analysis. From the digital photographs of samples, it is foreseen that, SrCe0.98Sm0.02O3 pumped using near UV LED chip can be used for commercial white light generation.

Measuring physical literacy for an evidence-based approach: Validation of the French perceived physical literacy instrument for emerging adults

Background/ObjectivesPhysical Literacy (PL) is increasingly recognized as a key element in studies aimed at promoting Physical Activity (PA), but measurement tools for emerging adults and evidence for assessing and using this concept is lacking in a wide range of contexts. We aimed to validate the French version of the Perceived Physical Literacy Instrument (PPLI): a scale for investigating PL in young French adults. MethodsAfter PL and PA data collection (n = 2,248, agemean = 19 ± 1.53 yrs), exploratory and confirmatory factor analyses, Cronbach's α and Omega's ω and an Intraclass-Correlation analysis were undertaken. Spearman's rank correlation and the Boruta algorithm were used to investigate the association between PL and PA. Boruta's algorithm examined deeper external validation by analyzing the strength of an overall PL score in explaining PA, compared with separate dimensions of PL and individual characteristics (BMI, sex). ResultsResults showed an acceptable level of reliability (ICC = 0.91), internal validity (α = 0.88; ω = 0.77), and external validity (Rhô >0.18, p < 0.01). The Boruta algorithm highlighted that the construct of PL is a significant predictor of PA, although not the strongest one which is social and affective dimension. ConclusionThis study provided data on validity and reliability of the first French assessment tool to measure PL constituted by four intertwined dimensions (physical, cognitive, social, affective). At the same time, it provides new evidence of the association between PL and PA.

Role of position specific Ga and N vacancy related defects by ion irradiation in tailoring the ferromagnetic properties of thin GaN films: An experimental and first principle-based study

The variation in ferromagnetism caused by position-specific point defects in GaN (100 nm) thin films is reported here. We observe a systematic variation of magnetic properties in GaN films after 300 KeV Xe+ ion irradiation with different fluences, i.e., 5 × 1012, 5 × 1013, and 5 × 1014 ions-cm−2. Metal Organic Chemical Vapor Deposition (MOCVD) grown Pristine GaN thin film contains Ga vacancies and related defects (as analysed by photoluminescence study) and shows a magnetic moment of ∼ 0.99 emu/g at room temperature. The GaN (002) peak intensity in XRD data decreases with increasing irradiation fluences, confirming that both Ga and N have been removed from their lattice sites and that the content of both Ga and N in irradiated samples has been reduced compared to the as-deposited one. It is evident from the PL data that Ga vacancy-type defects are maximum in pristine samples, after ion beam irradiation the appearance of some new peaks in the photoluminescence data indicates the creation of some new types of defects. The XPS data (Ga 3d and N 1s) also reveals that the intensity of the peak corresponding to Ga bonded with N decreases with higher irradiation doses. This reveals that Ga and N content have been decreased after ion irradiation. The orderly decrease of magnetic moment with increasing ion fluence is possibly due to the isolated Ga vacancies in the pristine film as it has the minimum formation energy and maximum magnetic moment as evident from Density Functional Theory (DFT) results. Therefore, the pristine GaN shows the maximum magnetic moment and, after ion beam irradiation, the creation of Ga vacancies at adjacent sites and other point defects is favourable as pristine GaN already contains Ga vacancies at random sites. DFT results further show that the magnetic moment decreases for other defect configurations rather than the isolated Ga vacancies.

FRET mechanism to enhance the quantum yield of the PCz/gC3N4 nanocomposite, an emissive material for OLED applications.

Conjugated polymers such as polycarbazole (PCz) have captivated more attention than other carbazole-based derivatives due to their superior electrical and optical properties. Accordingly, we synthesized PCz/gC3N4 nanocomposites via the in situ polymerization method using FeCl3 as the oxidative reagent. The synthesized nanocomposites were subjected to characterization techniques to examine their optical and electrical parameters and decide whether the materials were suitable as emissive materials. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) were carried out to ascertain the crystalline or amorphous nature, surface interactions, and functional groups present in them. The surface microstructural and topographical investigations were conducted using field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (HRTEM) techniques. Optical parameters, such as refractive index ∼2.06, optical absorbance, optical band energy ∼2.77 eV, and the photoluminescence emission range, were studied using UV-Visible and photoluminescence spectrometry. The theoretical relative emission quantum yield of ∼67.9% and 87.7% energy transfer from the donor to the acceptor ion via the Förster energy transfer mechanism are illustrated by the PL data. The Förster energy transfer mechanism has been elaborated. The carrier mobility ∼32.03 m2 V-1 S-1, sheet resistance ∼1.6977 × 102 Ω m, carrier density ∼11.96 × 1014 cm-3 and conductivity ∼5.90 × 10-3 S cm-1 were computed using Hall effect measurements. The dielectric constant, dielectric loss, and IV characteristic curve were estimated by the LCR and Four-probe IV measurement methods. The high PL emission intensity, CIE coordinates in the blue emission region, and the CCT value indicate that it is a suitable emissive layer material for OLED applications.

Structural and luminescent characteristics of orthorhombic GdAlO3:Sm3+ nanocrystalline materials for solid state lighting

In the current article, an eco-friendly, efficient and less energy consuming gel-combustion process has been used to develop a series of perovskite based Gd1-xAlO3:xSm3+ (x = 0.01, 0.03, 0.05, 0.07 and 0.09 mol) nanomaterials which produce reddish orange light. According to crystallographic investigation, the synthesized nanocrystalline materials belong to orthorhombic crystal symmetry having space group Pnma (62). The non-uniform agglomerated particles in nano range (35–45 nm) were examined via TEM analysis, which supports the results obtained from XRD analysis. The PL spectra involve 4f-transitions of trivalent samarium ions, such as 4G5/2→ 6H5/2 (565 nm), 4G5/2→ 6H7/2 (601 nm) and 4G5/2 → 6H9/2 (647 nm). The energy transferal mechanism between neighbouring trivalent samarium ions is dipole–dipole (DD) interaction, which is answerable for the quenching of luminous intensity. Additionally, colorimetric characteristics like color coordinates, color-purity and correlated-color temperature were obtained using PL data. These photometric parameters were strongly recommends these synthesized nanophosphors samples for solid state lighting applications.

Analysis and characterization of GaN nanostructure by electrochemical etching

Nanostructured GaN layers have been fabricated by electrochemical and laser-induced etching (LIE) processes based on n-type GaN thin films grown on the Si (111) substrate with AlN buffer layers. The effect of varying current and laser power density on the morphology of the GaN layers is investigated. The etched samples exhibited a dramatic increase in photoluminescence intensity as compared to the as grown samples. The average diameter of the GaN crystallites was about 7–10 nm, as determined from the PL data The Raman spectra also displayed stronger intensity peaks, which were shifted and broadened as a function of etching parameters. A strong band at 522 cm−1 is from the Si (111) substrate, and a small band at 301 cm−1, due to the acoustic phonons of Si. Two Raman active optical phonons are assigned h-GaN at 139 cm−1 and 568 cm−1due to E2 (low) and E2 (high) respectively.

Structural, morphological and optoelectronic aspects of YAlO3:Dy3+ doped nanocrystalline materials for NUV energized WLEDs

Cost-effective urea assisted solution combustion (SC) synthetic method was employed to prepare a series of doped YAlO3:xDy3+ (0.01–0.08 mol) phosphors. The resulting powdered samples were comprehensively examined through various structural as well as optical measurements. Rietveld refinement studies concluded that prepared nanomaterials structured into the orthorhombic system having Pbnm (62) space group. Energy dispersive spectral (EDS) analysis was executed to observe the relative proportions of constituent elements in all doped nanophosphors. Transmission electron microscopy (TEM) micrograph indicated the presence of agglomerated particles with the average size in the nano range. Photoluminescence excitation (PLE) spectra showed that the designated phosphors could be excited by near ultraviolet (NUV) energized lighting sources. The strongest emission centred at 576 nm, corresponding to electric dipole (4F9/2 → 6H13/2) transition of Dy(III) ion. Furthermore, characteristics photometric parameters viz. correlated color temperature (CCT), chromaticity coordinates (x and y), and color purity (%) were figure out with the aid of PL data, which strongly endorsed their usage in NUV energized WLEDs applications.

Balance Evaluation and Gait Analysis After Arthroscopic Partial Meniscectomy.

The purpose of this study is to investigate how walking and balance are affected at different time intervals after arthroscopic partial meniscectomy (APM). Forty-five patients with APM and a healthy control group of 46 people were included in the study. Gait and bipedal balance analysis were performed to the patient group twice in 4 weeks and 12weeks after surgery. In the gait analysis performed after 4 weeks, stance phase (SP), step time (ST), and total double support (TDS) were higher, and step length (SL), swing phase (SWP), cadence (C), and speed (V) in the patient group were lower. After 12weeks, SP, TDS, and step width (SW) data were higher in the patient group and SWP was lower. In both measurements, the gait of the patient group is not symmetrical. In open-eye balance test, it was observed that the data of length of ellipse (LoE), area of ellipse (AoE), and path length of CoP (PL) were different after 4 weeks but these differences disappeared after 12weeks. Width of ellipse (WoE), LoE, AoE, and PL data were different in the test performed with eyes closed after 4 weeks. In addition to the same data after 12weeks, the medio-lateral direction (ML) was also higher than the patient group. After 12weeks, walking has not fully recovered. There was no difference in the balance analysis with eyes open, but the differences were still present in the eyes-closed analysis.

IMPACT OF Mn2+ IONS ON MICRO-STRUCTURAL, LUMINESCENCE PROPERTIES OF ZnS-MoS2 NANOCOMPOSITES FOR OPTOELECTRONICS

Bottom-up hydrothermal synthesis was used to prepare semiconducting natured undoped and Mn2+ doped nanocomposites of ZnS-MoS2. XRD -X-ray diffraction analysis, DRS- diffuse reflection spectroscopy spectrophotometer, FT-IR-Fourier transform infrared spectroscopy, SEM-scanning electron microscopy, and PLphotoluminescence techniques were used to characterize the structural, optical absorption, morphological, IR spectral, and luminescence properties of prepared powder samples. The average crystallite size of prepared nanocomposites ranged between 12 and 20 nm. The FT-IR spectra were used to examine the molecular vibrations and various functional groups contained in the prepared samples. Surface morphology analyses show the presence of spherical-shaped ZnS flakes and hexagonal MoS2 flakes. The energy bandgap decreases as the quantity of Mn2+ doping in the host lattice increases, showing the quantum confinement of prepared samples. The PL data indicates a characteristic luminescence peak in the yellow-orange region at 585 nm.

Europium doping of cadmium selenide (CdSe) quantum dots via rapid microwave synthesis for optoelectronic applications.

The tunability of optical properties in inorganic semiconductor quantum dots (QDs) allows them to be exceptional candidates for multiple optical and optoelectronic applications. While QD size dictates these properties, the addition of highly luminescent rare-earth elements also affects absorption and emission properties. In this work, we were able to successfully synthesize europium-doped CdSe QDs using a one-pot microwave synthesis method. Using recipes that we previously developed, we were able to synthesize Eu3+:CdSe quantum dots and tune their optical properties by varying microwave irradiation temperatures, hold times, and dopant concentration. UV-Vis spectroscopy and photoluminescence data show that structural incorporation of europium has an effect on the optical properties of CdSe QDs via energy transfer from host to dopant. Eu3+:CdSe QDs have diameters ranging from 4.6-10.0 nm and colors ranging from blue-green to dark red. The development of recipes for high throughput rapid microwave synthesis allows for QDs to be synthesized with repeatability, tunability, and scalability.

Studying of the pressure-induced photoluminescence characteristics of CsPbI3 nanocrystals

The carrier dynamics and the radiative channel together govern the performance of optoelectronic devices based on perovskite nanocrystals (NCs). In order to further understand their relationship, the pressure-dependent spectral test is employed, which scans the photo-physical properties of CsPbI 3 NCs. The carrier dynamics involving monomolecular and bimolecular recombination slow down with pressure, which decreases the photoluminescence quantum yield (PLQY). The former is affected by the variance of the shallow defect and both of them are sensitive to the phase transition at 0.39 GPa, which is confirmed by the pressure-dependent PL and absorption spectral data. The radiative lifetime, originated from a part of bimolecular recombination, prolongs with pressure, even though the PLQY decreases simultaneously. The photo-physical characteristics as mentioned is mainly originated from the lattice shrinkage induced by pressure. Our work provides clues for optimizing the performance of lighting and displaying devices based on inorganic perovskites NCs. • The photo-physical characteristics of CsPbI 3 NCs under high pressure is studied by many types of spectral tests. • The CsPbI 3 NCs undergo a phase transition at 0.39 GPa. • With pressure, the PL quantum yield (QY) of CsPbI 3 NCs decreased significantly. • Pressure affects the competition between radiative and non-radiative channels of CsPbI 3 NCs.

Comparative study of quantum confinements effect present in Silicon Nanowires using absorption and Raman spectroscopy

Silver-induced chemical etching (SIE) has been widely explored for developing silicon (Si) based photovoltaic devices with its benefits for low-cost and large-area fabrication of silicon nanowires (SiNWs) of high aspect ratios. Structures and optical properties of SiNWs fabricated through chemical etching are significantly affected by experimental as well as environmental conditions of etching. A comparative study of quantum confinement (QC) effect due to variation in nano crystallite size (NCS) of SiNWs samples, fabricated by SIE technique has been investigated here using ultraviolet visible (UV-VIS) spectroscopy and Raman spectroscopy. An enhanced optical band gap has been observed from the samples under UV excitation at room temperature due to QC effect. To improve the understanding of basic mechanism of QC effect present in samples has been analyzed through characteristic features of Raman line-shape like red shift, asymmetry ratio and broadening as compared to its bulk counterpart. The NCS of SiNWs present in the samples has been calculated by QC based Brus model, bond polarizability (BP) model and Raman line-shape fitting model. This study prove itself to explore a new direction towards a systematic building block for fabricating optoelectronic devices based on light - matter interactions present at the nano-scale. • Silicon nanowires (Si-NWs) onn type-Si(100) by silver-induced chemical etching. • Results obtained, indicate that the fabrication of size controlled Si-NWs. • Quantum confinements effectobserved in Si-NWs using Brus, bond polarizability and line shape model. • Estimated size from Brus and bond polarizability model using PL and Raman data were around 1.7–3.2 nm. • Theoretical estimation of size from line shape model were 2.66–3.16 nm.