Nano Pyramids Research Articles

Electro-Structured Cu Distorted Nanopyramids for Superior Sweat Glucose Sensing

There is a rising global demand for non-invasive glucose monitoring devices, due to an increase in diabetes and its associated health problems. Nanostructures, including needles, fibers, and rods, have drawn considerable attention due to their unique structural-based physical and chemical features in non-enzymatic electrochemical sensing. Copper is a potential candidate for applied research because of its higher electrical conductivity, low cost, and strong reactivity. To create 3-D nano copper structures, researchers have investigated chemical, electrochemical, and hydrothermal techniques. The electrochemical method can better control the formation reaction for these structures. The electrochemical process has better control over the formation reaction for these structures.Distinctive and self-supported copper nanopyramids were electrochemically created on a copper substrate within a few seconds by electrochemical deposition in a one pot synthesis. The SEM image of the constructed nano copper pyramids are shown in figure 1a. The built nano pyramids have a length of ~200 nm. The generated nanostructures display excellent catalytic activity for non-enzymatic glucose sensing. The created nonenzymatic sensor was tested for glucose detection in synthetic sweat and it displayed a linear response in the range of 20 µM- 2000 µM, making it appropriate for practical applications. The chrono amperometry for glucose sensing was performed at 0.5V for 60s. Figure 1b shows the calibration plot for glucose sensing. Linear response for the glucose was observed in the range from 20µM – 2000µM. The device showed a very low interference for uric acid and ascorbic acid. The device is stable upto 60 days, highly reproducible and can be reused upto 5 times. The correlation coefficient was 0.9857 for the linear equation I(μA) = (9.52*10-3) *C (in µM) + 5.065 and a sensitivity of 1.17 nA/(μM-cm2) was observed Figure 1

Surface-dependent CO oxidation over Au/ZnO nanopyramids and nanorods

The catalytic activity of metals is very sensitive to the surface orientation of supporting oxides but rather little is known about ZnO in this regard. Nanostructured support morphologies present an attractive research strategy there because they allow probing the catalytic impact of well-defined surfaces at ambient pressure. The predominant {101̅0} side planes of hexagonal ZnO nanorods (NR) are terminated with the same number of O and Zn atoms while both the (0001) basal and {101̅1̅} side planes of hexagonal ZnO nanopyramids (NPy) are Zn-terminated. STEM analyses reveal two Au//ZnO interfacial configurations for each system after deposition of ∼3 nm Au nanoparticles. CO oxidation proceeds 15 times faster over the Au/ZnO NR than the Au/ZnO NPy catalyst at room temperature. The difference in catalytic activity can be traced to facilitated CO activation at the interfacial sites of Au/ZnO NR while it is retarded due to co-adsorption of CO with CO32- at undercoordinated Zn2+ ions of the interfacial perimeter of Au/ZnO NPy according to CO DRIFTS analyses. These results demonstrate that the catalytic behavior of metal/ZnO systems are very sensitive to ZnO surface terminations and the associated metal//ZnO interface configurations.

Performance enhancement using an embedded nano-pyramid in a perovskite solar cell with TaTm as a hole transport layer

The trapping of photons and broad-spectrum absorption of solar irradiance are the primary focus of numerous solar cell research applications.

Geometric optimization and performance enhancement of PEDOT: PSS/GaAs NP array based heterojunction solar cells

Polymer/semiconductor nanostructure array based solar cells (SCs) exhibit extremely low optical losses, excellent light-harvesting, improved carrier lifetime, increased defect tolerance etc. and can be a new pathway for low-cost high efficiency SCs. In order to fabricate efficient heterojunction SCs, it is extremely necessary to evaluate their optimal geometric configuration theoretically. In this article, using 3D-finite difference time domain (FDTD) method, we have optimized the geometric configuration of poly (3, 4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT: PSS) coated vertically aligned GaAs Nano pyramid (NP) array heterojunction SCs to obtain high average optical absorption and J sc of 92.2% and 41.1 mA/cm 2 , respectively. The optimized structure simulated in Lumerical Charge Solver DEVICE module, exhibit power conversion efficiency (PCE) of 15.9% despite low carrier mobility and lifetime of 1000 cm 2 v −1 s −1 and 2ns respectively. • Role of GaAs nanopyramids (NPs) in efficient light harvesting is studied. • Optimization of geometrical dimensions of the NPs is performed in terms of optical J sc . • Conformal coating of PEDOT:PSS results in absorption enhancement. • GaAs NPs/PEDOT PSS based solar cells exhibits PCE of ~13%.

Design of InP-based truncated nanopyramid solar cells with conformal coating of PEDOT: PSS for improved light harvesting efficiency

III-V nanostructure-based solar cells (SCs), with remarkable performance improvement in recent years, are considered as promising candidates for next-generation photovoltaics. In this paper, we present a simulation study of a new structure of PEDOT:PSS/InP truncated nanopyramid (TNP) Hybrid Solar Cell (HSC) using a finite difference time domain (FDTD) method. In the TNP-HSC, the nanopyramids (NPs) are flattened from the top to increase the photon capturing capability and then the TNPs are coated with PEDOT:PSS to enhance the light absorption in the long-wavelength region of solar spectral irradiance. Besides, to delineate the mechanism of photo-absorption enhancement in the proposed structure, a rigorous analysis of the electric field and photo-generation rate profiles at different wavelengths is performed. The simulation results show that the PEDOT:PSS coated of InP TNP exhibits better performance than uncoated InP NP SCs or planar counterpart. In addition, the optimization of the geometrical parameters of InP TNPs, including period, lattice constant, top surface flatness, and coating thickness, leads to the power conversion efficiency of 24.73%, which is 1.8 times greater than its planar counterpart. • Role of nanopyramids in PEDOT:PSS/InP solar cells studied using FDTD method. • Optimization of nanostructure done in terms of optical Jsc. • Truncated nanopyramids exhibit better absorption than pointed nanopyramids. • Electrical Jsc of 27 mA/cm2 is obtained with ITO/InP TNP/Al Solar cell structure. • Photo Conversion Efficiency (PCE) of 24.73% is achieved with our optimized.

Performance enhancement of Nanopyramid based Si hybrid solar cells utilizing the plasmonic properties of oxide coated Metal Nanoparticles

In this paper, we have analyzed the role of single and dual nanostructures embedded in PEDOT:PSS (Poly (3,4-ethylenedioxythiophene):poly (styrenesulfonate))/c-Si Hybrid Solar Cells (HSCs) using Finite Difference Time Domain (FDTD) method. HSC structures with Nanopyramids (NPs) on top of the Si substrate exhibit optical J sc of 35.91 mA/cm 2 . We obtained significant improvement in J sc by 1.56% and 14% observed with the insertion of oxide coated Ag MNPs (Metal Nanoparticles) and Al MNPs in the rear and front end of the HSC, respectively. A comparative analysis of these three structures denoted as NP (for nanopyramids only), NP + Ag MNPs (nanopyramids with Ag MNPs embedded in the front end of the HSCs along with oxide coated MNPs in the rear end) and NP + Al MNPs (same as the second structure with Ag MNPs replaced with Al MNPs) shows that HSCs with NP + Ag MNPs and MoO 3 coating achieve the highest open circuit voltage (V oc ) of 0.7 V, electrical J sc of 22.19 mA/cm 2 , power conversion efficiency (PCE) of 12.56% and Fill Factor (FF) of 80.85%. • Role of nanostructures in PEDOT:PSS/c-Si solar cells studied using FDTD method. • Optimization of nanostructure done in terms of optical J sc . • J sc of 35.91 mA/cm 2 obtained with Nanopyramids (NPs) on top of the Si substrate. • NPs with metal nanoparticles at rear and back end of Si exhibits best PCE.

Light-trapping strategy for PEDOT:PSS/c-Si nanopyramid based hybrid solar cells embedded with metallic nanoparticles

In this article, we have investigated the combined role of nanopyramid (NP) array and metal nanoparticles (MNPs) in enhancing the light trapping ability and improving the photo-absorption of PEDOT:PSS/c-Si Hybrid Solar Cells (HSCs) using a 3D finite-difference time-domain (FDTD) method. A parametric optimization of the essential geometrical parameters of NPs and MNP is performed based on short circuit current density (Jsc). The optimization result reveals that maximum Jsc of 35.91 mA/cm2 is achievable with top textured NP (without MNPs) which is 24.38% higher than the planar counterpart. However, the absorption spectrum is broadened with the insertion of Al MNP at rear side of the HSC. This is also accompanied by almost two fold increase in Jsc to 41.71 mA/cm2 which is 44.47% higher the planar HSCs. The photovoltaic parameters such as Jsc, Voc, PCE and Fill Factor (FF) are calculated using the DEVICE software for NP and NP embedded with Al MNPs based c-Si Solar Cells. The physics at the interface of inorganic nanostructure and organic material layer is thoroughly described. In addition to this, we have tried to decode the underlying physics for the enhancement of photon absorption in nanopyramidal structures and MNPs structures through an extensive analysis of the photogeneration rate, electric field intensity, power absorption profiles, PCE and FF of nanopyramidal, nanopyramidal with MNP and planar HSCs.

Enhancement of light trapping for ultrathin crystalline silicon solar cells

The discussion of ultrathin crystalline silicon solar cell (UCSC) thickness and light enhancement patterns has long been a practical topic in its field with the objective of achieving optimum efficiency. In this work, we distinguish between the effects of the top and bottom structural designs on the light absorption of ultrathin crystalline-silicon solar cell. Nanopyramid (NP) front surface and distributed Bragg Reflector (DBR) bottom layer as enhancement agent was combined and its relation with thickness of solar cell was studied thoroughly. The relationship of photonic interaction between the top and bottom surfaces is also examined. Based on our simulation results, the optimized cell architecture consists of a 4 μm-thick film combined with nanopyramid of 800 nm period and bottom reflector of 4 pair DBRs. The maximum achievable photo-current density of 36.72 mA/cm2 was obtained, which is among the best results of prior research for UCSC.

Fabrication of Nano Pyramid Texture on Ti-6Al-4V Using Nanosphere Lithography

Nanosphere lithography is a widely used technique for nanofabrication, due to its simple, effective, and inexpensive nature. This study presents the use of nanosphere lithography to produce nano-textured surfaces on Ti-6Al-4V.The effect of nanosphere diameter on the resulting nano-texture was tested by using two nanosphere diameters: 1 µm and 750 nm. Nanospheres were assembled into two substrate surfaces, and target material deposited using vapour deposition. The nanosphere mask was then removed to reveal nanopatterns on substrate surfaces. In general, samples that used a smaller nanosphere diameter produced sharper, more refined and consistent nanostructures, in comparison to samples tested with a larger nanosphere diameter. The results show successful fabrication of consistent and uniform arrays on different substrates. Ti-6Al-4V substrates allowed fabrication of nano pyramids, however these were not as uniform as glass, and more research needs to be completed to investigate the interaction between nanospheres and substrate material, and in forming more uniformly ordered arrays on Ti-6Al-4V. Consistency of nanopyramids can be improved by gaining more control over the nanospheres during mask the mask preparation stage. In addition, refining the nanoparticles can be achieved by using secondary processes, such as reaction ion etching. With further investigation and testing, this method, and study, may have applications in producing antibacterial surfaces, and reducing adhesion of bacterial cells to orthopaedic implant surfaces.

Electrochemical growth of controlled tip shapes of ZnO nanorod arrays on silicon substrate and enhanced photoluminescence emission from nanopyramid arrays compared with flat-head nanorods

Zinc oxide (ZnO) nanorod arrays (NRAs) with different morphologies such as; perfect hexagon flat-head, pyramidal, compact pencil, nail-shaped, and high-compact ZnO nanorod thin films, were successfully grown on silicon substrates. These NRAs were formed on substrates using a simple low-temperature electrochemical method without adding any catalyst or template via the precursors of zinc nitrate hexahydrate [Zn(NO3)2·6H2O] and hexamethylenetetramine [HMT; C6H12N4] with an equal molar concentration of 0.025 mol/l. The morphologies of the ZnO nanorods (NRs) could be controlled and transformed successfully in to other morphologies by changing the growth conditions, such as; growth temperature and applied current density. Detailed structural investigations reveal that the synthesized various NRs are single crystalline with wurtzite hexagonal phase and preferentially grow along the c-axis direction. The room temperature photoluminescence spectra show that each spectrum consists of an ultraviolet (UV) band and a relative broad visible light emission and infrared emission peak. The enhanced light emission intensity at UV peak (∼375 nm) is observed significantly from ZnO nanopyramid (NP) arrays because of the conical shape of NP. The photoluminescence intensity of the UV peak from the NPs is found to be 1.5–17 times larger than those from the other various NRs.

An Inverted Nano Pyramids and Grooves Surface for Surface Enhanced Raman Spectroscopy

An Inverted Nano Pyramids and Grooves Surface for Surface Enhanced Raman Spectroscopy

(Invited) Monolithic Integration of InP Based Structures on Silicon for Optical Interconnects

Monolithic integration of InP based structures on Si for optical interconnects is presented. Different strategies are demonstrated to achieve requisite InP platform on Si. In the first strategy, defect free isolated areas of epitaxially and laterally overgrown InP are obtained on Si and the InGaAsP based quantum wells directly grown on these templates have shown high material quality with uniform interfaces. In the second strategy, selective area growth is exploited to achieve InP nano pyramids on Si which can be used for the growth of quantum dot structures. In the third and the final strategy, a method is presented to achieve direct interface between InP and Si using corrugated epitaxial lateral overgrowth.

Effect of thickness and Si substrate morphology in La0.7Sr0.3MnO3/Si thin films

Investigation has been made on atomic, electronic structures and magnetic properties of La0.7Sr0.3MnO3 (LSMO) on Si substrate. The effect of different thickness of LSMO and different morphological [flat and nano-pyramid (NP)] of Si substrate are studied in present work. The result of Mn K-edge extended x-ray absorption fine structure indicates the more disorder of local atomic structure of first shell (Mn-O bound) in the thinner LSMO/Si film. The Mn L3,2-edge x-ray absorption near-edge structure shows the presence of Mn2+ ion on the sample. Furthermore, the Mn L3,2-edge x-ray magnetic circular dichroism reveals that the thinner film (LSMO/Si) has highest magnetic moment, in comparison to that of thick LSMO/Si and LSMO/Si-NP samples. This finding suggests that the appearance Mn2+ may play an important role in magnetic behavior of hetero-junction LSMnO/Si and Si-NP.

Highly flexible, transparent and self-cleanable superhydrophobic films prepared by a facile and scalable nanopyramid formation technique

A facile and scalable technique to fabricate optically transparent, mechanically flexible and self-cleanable superhydrophobic films for practical solar cell applications is proposed. The superhydrophobic films were fabricated simply by transferring a transparent porous alumina layer, which was prepared using an anodic aluminium oxidation (AAO) technique, onto a polyethylene terephthalate (PET) film with a UV-curable polymer adhesive layer, followed by the subsequent formation of alumina nano pyramids (NPs) through the time-controlled chemical etching of the transferred porous alumina membrane (PAM). It was found experimentally that the proposed functional films can ensure the superhydrophobicity in the Cassie-Baxter wetting mode with superior water-repellent properties through a series of experimental observations including static contact angle (SCA), contact angle hysteresis (CAH), sliding behaviour on the tilted film, and dynamic behaviour of the liquid droplet impacting on the film. In addition to the superior surface wetting properties, an optical transmittance of ∼79% at a light wavelength of 550 nm was achieved. Furthermore, there was no significant degradation in both the surface wetting properties and morphology even after 1500-cycles of repetitive bending tests, which indicates that the proposed superhydrophobic film is mechanically robust. Finally, the practicability of the proposed self-cleanable film was proven quantitatively by observing the changes in the power conversion efficiency (PCE) of a photovoltaic device covering the film before and after the cleaning process.

低能离子束诱导Ag表面纳米金字塔微结构

Ion beam sputtering induced experimental method was used to assist the silver film deposition on monocrystalline silicon(100)and the induced deposition effects of low energy Ar+ion beams was discussed with different ion energies,fluxes and substrate temperatures at the ion incidence angle of 30°.The experiment indicated that temperature change had significant influence on the nano microstructure size and roughness.When the substrate temperature was between 32℃ and 100℃,the closely packed nano pyramid microstructures were obtained with grains consistent in size;when the substrate temperature rose between 32℃and 200℃,the microstructures transverse size(λc)of samples increased rapidly,but the roughness decreased at first(32~100℃),and then increased rapidly(100~200℃).When ion flux density was within 15~45μA/cm2 with an ion beam energy of 1 400eV,the increase of ion beam flux densities at the same deposition temperature could achieve the nano crystal grains with unchanged lateral sizes and more compact arrangement,and slightly increased roughness;when ion beam energy was within 1 000~1 800eV with an ion beam flux of 15μA/cm2,the increase of ion beam energies could lead silver nano microstructure sizes to increase,and the surface roughness of samples to increase first and then decrease slowly.The pattern transformation of self-organizing nano-structure results from the interaction of spurting roughening and relaxation mechanism.

低能离子束诱导Ag表面纳米金字塔微结构

Ion beam sputtering induced experimental method was used to assist the silver film deposition on monocrystalline silicon(100)and the induced deposition effects of low energy Ar+ion beams was discussed with different ion energies,fluxes and substrate temperatures at the ion incidence angle of 30°.The experiment indicated that temperature change had significant influence on the nano microstructure size and roughness.When the substrate temperature was between 32℃ and 100℃,the closely packed nano pyramid microstructures were obtained with grains consistent in size;when the substrate temperature rose between 32℃and 200℃,the microstructures transverse size(λc)of samples increased rapidly,but the roughness decreased at first(32~100℃),and then increased rapidly(100~200℃).When ion flux density was within 15~45μA/cm2 with an ion beam energy of 1 400eV,the increase of ion beam flux densities at the same deposition temperature could achieve the nano crystal grains with unchanged lateral sizes and more compact arrangement,and slightly increased roughness;when ion beam energy was within 1 000~1 800eV with an ion beam flux of 15μA/cm2,the increase of ion beam energies could lead silver nano microstructure sizes to increase,and the surface roughness of samples to increase first and then decrease slowly.The pattern transformation of self-organizing nano-structure results from the interaction of spurting roughening and relaxation mechanism.

Selective self-assembly and characterization of GaN nanopyramids on m-plane InGaN/GaN quantum disks

Semiconductor nanopyramids (NPs) provide advantages in the development of novel functional optoelectronic devices due to their unique size-dependent properties. Here we demonstrate a new method for the fabrication of selectively self-assembled single-crystalline GaN NPs on the m-plane of periodically strained GaN/InGaN multiquantum disks embedded in the middle of GaN nanorods. The GaN NPs, which have ∼100 nm diameters and heights, are observed by scanning electron microscopy and their crystalline structure is confirmed by high-resolution transmission electron microscopy. Experimental analysis directly reveals the strain distribution along the growth direction of the NPs. Cathodoluminescence measurements on a single NP show that its emission energy redshifts compared with that of bulk GaN, corroborating the results showing the formation of tensile strain in the NP. Observations of the uniform distribution and localization of these NPs show the possibility of further tuning their size and density by controlling periodically strained nanorod surfaces.

Large-area nanogap plasmon resonator arrays for plasmonics applications

Large-area (∼8000 mm(2)) Au nanogap plasmon resonator array substrates manufactured using maskless laser interference lithography (LIL) with high uniformity are presented. The periodically spaced subwavelength nanogap arrays are formed between adjacent nanopyramid (NPy) structures with precisely defined pitch and high length density (∼1 km cm(-2)), and are ideally suited as scattering sites for surface enhanced Raman scattering (SERS), as well as refractive index sensing. The two-dimensional grid arrangement of NPy structures renders the excitation of the plasmon resonators minimally dependent on the incident polarization. The SERS average enhancement factor (AEF) has been characterized using over 30 000 individual measurements of benzenethiol (BT) chemisorbed on the Au NPy surfaces. From the 1(a(1)), β(CCC) + ν(CS) ring mode (1074 cm(-1)) of BT on surfaces with pitch λ(g) = 200 nm, AEF = 0.8 × 10(6) and for surfaces with λ(g) = 500 nm, AEF = 0.3 × 10(7) from over 99% of the imaged spots. Maximum AEFs > 10(8) have been measured in both cases.

N-InAs Nanopyramids Fully Integrated into Silicon

InAs with an extremely high electron mobility (up to 40,000 cm(2)/V s) seems to be the most suitable candidate for better electronic devices performance. Here we present a synthesis of inverted crystalline InAs nanopyramids (NPs) in silicon using a combined hot ion implantation and millisecond flash lamp annealing techniques. Conventional selective etching was used to form the InAs/Si heterojunction. The current-voltage measurement confirms the heterojunction diode formation with the ideality factor of η = 4.6. Kelvin probe force microscopy measurements indicate a type-II band alignment of n-type InAs NPs on p-type silicon. The main advantage of our method is its integration with large-scale silicon technology, which also allows applying it for Si-based electronic devices.

Optical and microstructural properties of self-assembled InAs quantum structures in silicon

Abstract The InAs quantum structures were formed in silicon by sequential ion implantation and subsequent thermal annealing. Two kinds of crystalline InAs nanostructures were successfully synthesized: nanodots (NDs) and nanopyramids (NPs). The peaks at 215 and 235 cm−1, corresponding to the transverse optical (TO) and longitudinal optical (LO) InAs single-phonon modes, respectively, are clearly visible in the Raman spectra. Moreover, the PL band at around 1.3 µm, due to light emission from InAs NDs with an average diameter 7±2 nm, was observed. The InAs NPs were found only in samples annealed for 20 ms at temperatures ranging from 1000 up to 1200°C. The crystallinity and pyramidal shape of InAs quantum structures were confirmed by HRTEM and XRD techniques. The average size of the NPs is 50 nm base and 50 nm height, and they are oriented parallel to the Si (001) planes. The lattice parameter of the NPs increases from 6.051 to 6.055 Å with the annealing temperature increasing from 1100 to 1200°C, due to lattice relaxation. Energy dispersive spectroscopy (EDS) shows almost stoichiometric composition of the InAs NPs.