Lumerical Software Research Articles

Silicon carbide synthesized by RF magnetron sputtering in the composition of a double layer antireflection coating SiC/MgF2

In this paper, the optimal thickness of SiC film for an antireflection coating was determined by computer simulations using Lumerical FTDT and SCOUT software. The simulation was carried out for the SiC/MgF2 system, where silicon carbide films were deposited at a magnetron power of 100, 150, 200, 250 W, while the thickness of the magnesium fluoride films remained unchanged and amounted to 130 nm. The simulation results showed that the optimal parameters for the synthesis of SiC antireflection layer are 100 W/50 nm. With these parameters, the reflection is less than 3% in the widest wavelength range of 475–1020 nm. The dependence of the physical properties of the synthesized films on the power of the magnetron is investigated. Using reflection and transmission spectroscopy it was experimentally revealed that a decrease in the magnetron power from 250 to 100 W leads to a decrease in the refractive index. According to our results the best antireflection effect can be achieved with SiC/MgF2 coatings when SiC films are deposited at 100 W magnetron power. The reflectance spectra are consistent with the simulation spectra, especially in the 475–1020 nm range, where the surface reflects only 0.2–3.0% of the incident light. The obtained results are explained by the correlation between the structural properties, composition of amorphous silicon carbide films and antireflection properties.

Label free identification of the different status of anemia disease using optimized double-slot cascaded microring resonator

An optical-based label-free biosensors including two indirectly coupled double-slot-waveguide-based microring resonator was designed and optimized for sensing purpose. Then, the optimized system was applied for the detection of hemoglobin concentration in anemia disease. The results were simulated based on the variational finite-difference time domain (varFDTD) method using the Lumerical software (Mode solutions) and the optimum geometrical parameters were determined to realize an optimum light transmission via the sensor. Nine different concentrations of hemoglobin in men and women were applied into the sensor and the status of anemia was identified based on the patients’ gender and different status of anemia disease, including the normal, mild, moderate, severe and life-threatening status. A sensitivity as high as 1024 nm/RIU with the minimum deflection limit of 4.88 × 10–6 RIU were measured for this biosensor, which introduces a high precision and micro-scale lab-on-a-chip micro device for health monitoring of the anemia.

Electrical performance of efficient quad-crescent-shaped Si nanowire solar cell

The electrical characteristics of quad-crescent-shaped silicon nanowire (NW) solar cells (SCs) are numerically analyzed and as a result their performance optimized. The structure discussed consists of four crescents, forming a cavity that permits multiple light scattering with high trapping between the NWs. Additionally, new modes strongly coupled to the incident light are generated along the NWs. As a result, the optical absorption has been increased over a large portion of light wavelengths and hence the power conversion efficiency (PCE) has been improved. The electron–hole (e–h) generation rate in the design reported has been calculated using the 3D finite difference time domain method. Further, the electrical performance of the SC reported has been investigated through the finite element method, using the Lumerical charge software package. In this investigation, the axial and core–shell junctions were analyzed looking at the reported crescent and, as well, conventional NW designs. Additionally, the doping concentration and NW-junction position were studied in this design proposed, as well as the carrier-recombination-and-lifetime effects. This study has revealed that the high back surface field layer used improves the conversion efficiency by sim 80%. Moreover, conserving the NW radial shell as a low thickness layer can efficiently reduce the NW sidewall recombination effect. The PCE and short circuit current were determined to be equal to 18.5% and 33.8 mA/hbox {cm}^2 for the axial junction proposed. However, the core–shell junction shows figures of 19% and 34.9 mA/hbox {cm}^2. The suggested crescent design offers an enhancement of 23% compared to the conventional NW, for both junctions. For a practical surface recombination velocity of 10^{2} cm/s, the PCE of the proposed design, in the axial junction, has been reduced to 16.6%, with a reduction of 11%. However, the core–shell junction achieves PCE of 18.7%, with a slight reduction of 1.6%. Therefore, the optoelectronic performance of the core–shell junction was marginally affected by the NW surface recombination, compared to the axial junction.

Quasi-hemispherical pit array textured surface for increasing the efficiency of thin-film solar cells

Enhancing light absorption is an important way for solar cells to increase the conversion efficiency. In this paper, we prepared a quasi-hemispherical pit array texture on the glass surface through the micro-fabrication process. Then, silicon thin-film (a-Si:H) solar cells were deposited on the other smooth surface. Pit array textured cells exhibit a higher short-circuit current density and power conversion efficiency than flat devices by ∼7% and 5%, respectively. The reflectance spectrum of textured solar cells is considerably reduced, and the external quantum efficiency is considerably improved in the 300–800 nm wavelength range. Through COMSOL Multiphysics and finite-difference time-domain (FDTD) simulation, three significant effects identify light-trapping characteristics for textured structures: surface reflection reduction, secondary absorption, and light scattering. As a result, the textured surface of the quasi-hemispherical pit array can considerably increase the efficiency of solar cells. Meanwhile, the Lumerical DEVICE software was used to simulate the electrical characteristics of the cell, and the experimental results were theoretically proven.

Numerical Study of Plasmonic Effects of Ag Nanoparticles Embedded in the Active Layer on Performance Polymer Organic Solar Cells

In this paper, the light absorption in the active layer of polymer solar cells (OPV) by using plasmonic nanocrystals with a hexagonal lattice structure is investigated. To study the relationship between the performance of the OPV solar cell and its active layer, a three-dimensional model of its morphology is utilized. Therefore, the three-dimensional (3D) finite-difference time-domain method and Lumerical software were used to measure the field distribution and light absorption in the active layer in terms of wavelength. OPV solar cells with bilayer and bulk heterojunction structured cells were designed using hexagonal lattice crystals with plasmonic nanoparticles, as well as core–shell geometry to govern a design to optimize light trapping in the active layer. The parameters of shape, material, periodicity, size, and the thickness of the active layer as a function of wavelength in OPV solar cells have been investigated. A very thin active layer and an ultra-thin shell were used to achieve the highest increase in optical absorption. The strong alternating electromagnetic field around the core–shell plasmonic nanoparticles resulting from the localized surface plasmon resonance (LSPR) suggested by the Ag plasmonic nanocrystals increased the intrinsic optical absorption in the active layer poly(3-hexylthiophene):phenyl-C61-butyric acid methyl ester (P3HT:PCBM). Based on the photovoltaic results, the short circuit current ranged from 19.7 to 26.7 mA/cm2.

Numerical analysis of InP based high efficiency radial junction nanowire solar cell

III-V nanowire (NW) solar cells (SCs) promise a comparable efficiency to that of their planar counterparts with additional advantage of reduced material consumption to cut the manufacturing cost. However, the disadvantage of low minority carrier lifetime due to the large surface-to-volume ratio of NWs degrades its photovoltaic performance to some extent. To overcome this issue, the structure of radial junction instead of axial junction for NWSCs has been used, but in experimental realization, defect density increases in the radial junction structure at the interface of core/shell, resulting in low performance. In this paper, we propose a high performance radial junction NWSC, consisting of p-InP NW coated by Ta 2 O 5 and ITO, and simulate it using Lumerical software. The results show that the use of ITO/Ta 2 O 5 shell over the InP NW as an electron selective contact enhances the absorption of incident photons, which in turn increases efficiency, also providing the condition that the InP required for core can be reduced without sacrificing the ideal current density, leading to a decrease in the fabrication cost. Besides, we investigate and compare the photovoltaic parameters of the structures of ITO/Ta 2 O 5 /p-InP NWSCs with circular and rectangular cross-section in terms of minority carrier life time, doping, and surface recombination velocity (SRV). It is found that circular and rectangular NWSCs with the same filling ratio possess almost the same optimized ideal photo-current such that for the carrier life time of 400 ps and the SRV of less than or equal to 10 4 cm/s at the interface of Ta 2 O 5 /InP, an efficiency as high as ~24.5% and ~25.6% can be achieved for circular and rectangular NWSCs, respectively. • Performance of cylindrical and rectangular InP NW studied using FDTD method. • Optimization of nanostructures is performed in terms of optical Jsc. • Oxide shell ITO/Ta 2 O 5 is used to enhance the absorption and J sc . • Influence of carrier lifetime, doping, and SRV on photovoltaic performance is investigated. • PCE of ~24.5% and ~25.6% is achieved with cylindrical and rectangular NW respectively.

Study of the Absorption of Electromagnetic Radiation by 3D, Vacuum-Packaged, Nano-Machined CMOS Transistors for Uncooled IR Sensing.

There is an ongoing effort to fabricate miniature, low-cost, and sensitive thermal sensors for domestic and industrial uses. This paper presents a miniature thermal sensor (dubbed TMOS) that is fabricated in advanced CMOS FABs, where the micromachined CMOS-SOI transistor, implemented with a 130-nm technology node, acts as a sensing element. This study puts emphasis on the study of electromagnetic absorption via the vacuum-packaged TMOS and how to optimize it. The regular CMOS transistor is transformed to a high-performance sensor by the micro- or nano-machining process that releases it from the silicon substrate by wafer-level processing and vacuum packaging. Since the TMOS is processed in a CMOS-SOI FAB and is comprised of multiple thin layers that follow strict FAB design rules, the absorbed electromagnetic radiation cannot be modeled accurately and a simulation tool is required. This paper presents modeling and simulations based on the LUMERICAL software package of the vacuum-packaged TMOS. A very high absorption coefficient may be achieved by understanding the physics, as well as the role of each layer.

Increasing the Quality Factor (Q) of 1D Photonic Crystal Cavity with an End Loop-Mirror

Increasing the quality factor (Q-factor) of an optical resonator device has been a research focus utilized in various applications. Higher Q-factor means light is confined in a longer time which will produce a sharper peak and higher transmission. In this paper, we introduce a novel technique to further increase the Q-factor of a one-dimensional photonic crystal (1D PhC) cavity device by using an end loop-mirror (ELM). The technique utilizes and recycles the transmitted light from the conventional 1D PhC cavity design. The design has been proven to work by using the 2.5D FDTD simulation with Lumerical FDTD and MODE software. By using the ELM technique, the Q-factor of a 1D PhC design has been shown to increase up to 79.53% from the initial Q value without the ELM. The experimental result shows that the device is measurable by adding a Y-branch component to the one-port structure and able to get a high Q result. This novel design technique can be combined with any high Q-factor and very high Q-factor designs to increase more Q-factor values of photonic crystal cavity devices or any other suitable optical resonator devices.

Significant Efficiency Enhancement in Ultrathin CZTS Solar Cells by Combining Al Plasmonic Nanostructures Array and Antireflective Coatings

In the few past years, the economic and eco-friendly Cu2ZnSnS4 (CZTS) solar cells have caught lots of attentions. However, due to rather poor efficiency, identifying deficiencies and making improvements is necessary. In the present study, the performance improvement of ultrathin CZTS solar cells was achieved through (1) incorporation of anti-reflective coating (ARC) on the surface of cell and (2) embedding Al plasmonic nanostructures with different radius, periods, and vertical positions in the absorber layer. Various thicknesses of CZTS absorber layer were simulated optically and electrically using FDTD and DEVICE solver of Lumerical software. The reference solar cell consists of a 1.5-nm-thick CZTS absorber and exhibit an efficiency of up to 5.67%, short-circuit current density (Jsc) of 18.48 mA cm−2 and open circuit voltage of 0.58 V. Result showed a remarkable performance enhancement of the solar cell in spite of a very thin absorber layer. For a 500-μm-thick CZTS solar cell with the assistance of ARC and embedding Al plasmonic nanostructures, the efficiency is increased to 7.45% due to an increase in Jsc to 22.62 mA cm−2 with an open circuit voltage of 0.62 V.

Double-peak one-dimensional photonic crystal cavity in parallel configuration for temperature self-compensation in sensing.

We designed and demonstrated a double-peak one-dimensional photonic crystal (1D PhC) cavity device by integrating two 1D PhCs cavities in a parallel configuration. The device design is proposed so that it can be used for bio-sensing purposes and has a self-compensation ability to reduce the measurement error caused by the change of the surrounding temperature. By combining two light resonances, two resonance peaks are obtained. The peak's separation, which gives the initial value for a sensing system, can be controlled by varying the cavity length difference (Δc) between the first and second 1D PhCs in parallel. Then, by making one arm of the device as the reference arm and the other arm as the sensing arm, the temperature self-compensation device can be realized. The design and simulation of this device are done by using Lumerical software, which are Lumerical MODE, Lumerical finite-difference time-domain, and Lumerical Interconnect. Electron-beam-lithography and deep reactive-ion-etching processes were used for device fabrication. The experimental results show the controllable peaks' separation, which solves the double-peak requirement for a temperature self-compensated bio-sensor design.

Investigation of SiC based antireflection coatings for Si solar cells by numerical FTDT simulations

In this paper, several computer simulations have been carried out using lumerical FTDT software. As a result, the optimal layer thicknesses for antireflection coatings SiC/MgF2 and SiC/ZnO/MgF2 deposited on the surface of polished silicon were determined. Among the considered coatings, the double layer structure SiC (60 nm) + MgF2 (110 nm) has the lowest reflection (<0.5%) in the range of 500–800 nm. Moreover, this SiC-containing coating has a lower reflection even in comparison with the widely used antireflection coatings ZnS/MgF2 and TiO2/SiO2. However, an analysis of the light absorption and short-circuit current density of a silicon solar cell made it possible to establish that among the considered antireflection coatings SiC/MgF2, SiC/ZnO/MgF2, ZnS/MgF2, and TiO2/SiO2, the most effective is the double layer structure SiC (50 nm) + MgF2 (110 nm) due to low reflectivity in the region 360–485 nm and maximum current density of 179.0 A/m2.

Characteristics of silicon nanowire solar cells with a crescent nanohole.

In recent years, newly emerging photovoltaic (PV) devices based on silicon nanowire solar cells (SiNW-SCs) have attracted considerable research attention. This is due to their efficient light-trapping capability and large carrier transportation and collection with compact size. However, there is a strong desire to find effective strategies to provide high and wideband optical absorption. In this paper, a modified circular nanowire (NW) with a nanocrescent hole is newly introduced and analyzed for solar cell applications. The crescent hole can strongly improve the light absorption through the NW due to the excitation of numbers of modes that can be coupled with the incident light. The material index, volume, and position of the nanohole are studied to significantly increase the optical absorption efficiency and hence the power conversion efficiency (PCE). The absorption performance can be further preserved by using a silicon substrate due to the coupling between the supported modes by the NW, and that of the substrate. The optical and electrical characteristics of the suggested design are investigated using finite difference time domain and finite element methods via Lumerical software packages. The reported asymmetric design offers higher optical and electrical efficiencies compared to the conventional NW counterpart. The proposed NW offers a short circuit current density (Jsc) of 33.85 (34.35) mA/cm2 and power conversion efficiency (PCE) of 16.78 (17.05) % with an enhancement of 16.3 (16.8) % and 17.3 (18.4) % for transverse magnetic (TM) and transverse electric (TE) polarizations, respectively, compared to the conventional cylindrical counterpart.

(Cu2O-Au) \u2013 Graphene - Au layered structures as efficient near Infra - Red SERS substrates

Near Infra-Red Surface Enhanced Raman Spectroscopy (NIR SERS) has gained huge attention in recent years as the conventional visible SERS suffers from overwhelming fluorescence background from the fluorophore resulting in the masking of Raman signals. In this paper, we propose a novel multi-layered SERS substrate- (Cu2O - Au) - Graphene – Au - for efficient NIR SERS applications. The proposed structure has a monolayer of Cu2O - Au core-shell particles on a Au substrate with 1 nm thick graphene spacer layer. Mie simulations are used to optimize the aspect ratios of core-shell particles to shift their plasmon resonances to NIR region using MieLab software. Further, Finite Difference Time Domain (FDTD) simulations using Lumerical software are used for the design of the multiparticle layered SERS substrate as MieLab software works only for single particle systems. Designed structure is shown to provide high field enhancement factor of the order of 108 at an excitation of 1064 nm thus ensuring the possibility of using the proposed structure as efficient NIR SERS substrate which could probably be used for various NIR sensing applications.

Electrical characteristics of modified truncated cone nanowire for efficient light trapping

In this paper, a novel design of truncated cone nanowires (NWs) solar cell (SC) with air gap is studied and analyzed. The optical and electrical characterizations are obtained using Lumerical finite difference time domain (FDTD) and Lumerical Device software packages. The modified truncated cone NWs have an upper air hole gap to increase the light confinement through the suggested design. In this study, ultimate efficiency, short circuit current density (Jsc), open circuit voltage (Voc), fill factor (FF) and power conversion efficiency (PCE) are calculated to compute the optoelectronics performance of the reported NWs. Moreover, the geometrical parameters of the studied design are adjusted to maximize the absorption through the modified structure. Furthermore, the Shockley-Read-Hall (SRH) lifetimes and doping concentrations are tuned to increase the PCE. The investigated NWs achieve an optical ultimate efficiency and Jsc of 42.74 % and 34.98 mA/cm2, respectively with an enhancement of 18.15 % over conventional conical NWs. Further, the radial doping of the reported design shows short circuit current density of 32.16 mA/cm2, open circuit voltage of 0.66 V and PCE of 15.36 %. An electronic implementation of the suggested NWs SC is also made using single diode model which shows a good agreement with the simulation results. Therefore, the suggested NWs design is a promising design for developing low cost and highly efficient SC.

Bi:YIG@Au magneto-plasmonic core-shell nano-grating with robust, high magneto-optical figure of merit

Abstract We numerically examine the role of Fano resonance for enhanced magneto-optical effect in an arrayed magneto-plasmonic core-shell structure composed of Bi:YIG cores as a magneto-optical active medium and Au sells as plasmonic ones. The optical and magneto-optical behavior of the magneto-plasmonic core-shell grating structure sustaining Fano resonance is investigated by means of Lumerical software based on the finite-difference time-domain solver. In the proposed structure, Fano resonance arises from the interplay between the guided mode and the surface plasmon resonance which results in enhanced magneto-optical Faraday effect. In addition, the Fano resonance and correspond enhanced magneto-optical effect can be tuned by changing the array period of the structure. The obtained results can be of interest in miniaturized and advanced magneto-optical devices.

Channel length scaling and electrical characterization of graphene field effect transistor (GFET)

&lt;p&gt;The exclusive monoatomic framework of graphene makes it as an alluring material to be implemented in electronic devices. Thus, using graphene as charge carrying conducting channel material in Field Effect Transistors (FET) expedites the opportunities for production of ultrasensitive biosensors for future device applications. However, performance of GFET is influenced by various parameters, particularly by the length of conducting channel. Therefore, in this study we have investigated channel length scaling in performance of graphene field effect transistor (GFET) via simulation technique using Lumerical DEVICE software. The performance was analyzed based on electrical characterization of GFET with long and short conducting channels. It proves that conducting channel lengths have vast effect on ambipolar curve where short channel induces asymmetry in transfer characteristics curve where the n-branch is suppressed. Whereas for output characteristics, the performance of GFET heavily degraded as the channel length is reduced in short channels of GFET. Therefore, channel length scaling is a vital parameter in determining the performance of GFET in various fields, particularly in biosensing applications for ultrasensitive detection.&lt;/p&gt;

Absorption spectra and electric field distributions of butterfly wing scale models coated with a metal film studied by finite-difference time-domain method

Inspired by alternative hybrid-biophotonic structures and modern computational electromagnetics in plasmonics, herein, we attempted to understand the plasmonic properties of a metal film (gold or palladium) on the surface features of butterfly wing scales, as they might represent the dominant features of structure-enhanced and/or structure-attenuated optical properties. Light-harvesting plasmonic antenna was loaded on these natural substrates. We examined the plasmonic properties of three models representing the scales of three lepidoptera species. Each scale model was assumed to have a 100 nm metal coating. In addition to the electron micrograph of the lepidopterans’ wings, the optical properties of the investigated structures were numerically studied using the finite-difference time-domain technique. We first constructed the biophotonic models of butterfly structures coated with a metal film, and then they were verified by scanning electron microscopy images using Lumerical Software, which provided an accurate solution of Maxwell’s equation for the micro/nanostructures. The metal samples were palladium or gold, while the investigated scales of butterfly species were Catopsilia pomona, Danaus genutia, and Cetbosia pentbesilea. Electric field and absorption spectra were observed under broadband light irradiations at perpendicular- and parallel-polarized light illuminations. As a result of the formation of variations of metals on the different features of wing scales, we observed changes in the absorption intensities and a redshift in the main peak absorbance. The spectra further showed a close relationship with the electric field distribution. A metal film coated on the butterfly wing scales acted as an optical plasmonic sensitivity to amplify and attenuate the visible light, whereas the existence of wave propagating modes from the well-defined structural variations resulted in a reduction and enhancement of the bandwidth of absorbance. Among the three simulation models, the Cetbosia pentbesilea scale model coated with a gold film demonstrated the best plasmonic properties to the electric field, in terms of its potential application for further biophotonic structure fabrication.

Effect of Yagi–Uda nano-antenna element shape on the directivity and radiation efficiency

In this paper, different optimal designs of Yagi–Uda nano-antennas (NAs) are introduced and analyzed based on different element shapes to maximize the directivity and radiation efficiency. The studied element shapes include triangular, hexagonal, cube, square, rotated square, rectangular, ellipsoid, and elliptical cylinder shapes. The NAs parameters for each design are optimized using particle swarm optimization algorithm to achieve high directivity at a wavelength of 500 nm for wireless point-to-point applications. The designs are numerically analysed using 3-D finite difference time domain method (3-D FDTD) via Lumerical software package. To illustrate the performance of the proposed antennas, different radiation parameters such as radiation pattern, directivity, and radiation efficiency have been studied. Moreover, a tolerance of ± 5% is calculated to consider the imperfections that may appear in the fabrication process at a nanoscale. The optimized rectangular prism NA achieves the highest directivity of 24.21 with an efficiency of 50.74%. However, the optimized triangular prism NA has the highest efficiency of 73% with a directivity of 20.89. This enhancement is mainly attributed to the efficient coupling between array elements along with low side lobe level. However, a trade-off between directivity and radiation efficiency is obtained by the hexagonal prism NA with directivity of 21.9 and radiation efficiency of 69.1%.

Modelling of a two-dimensional photonic crystal as an antireflection coating for optoelectronic applications

In article a two-dimensional photonic crystal (PhC) is considered and modelled as a new generation antireflection coating for optoelectronic devices. Traditional antireflective coatings (ARCs) reduce the reflection of the radiation only – the new generation of antireflective coatings should affect the distribution of the radiation also. Such functionality can be provided by the two-dimensional PhC which reduce the reflection and scatter transmitted light. Prior to the fabrication, the PhCs should be designed and analysed. Results of the analysis should provide quantitative means for choice of materials and design solutions. In work, we analyse the electromagnetic field distribution as Poynting vectors inside the materials of optoelectronic devices, in order to investigate the possibility of improving the construction of future optoelectronic devices. Furthermore, we calculate the reflection and transmission of that ARC. It’s a complex optic analysis of new generation of ARC. The numerical analysis has been performed with the FDTD method in Lumerical Software. In work, we consider the two-dimensional photonic crystal on the top surface of optoelectronic structures. We compared the results with the traditional ARC from these same parameters as PhC: thickness and material. As an example, we presented the application of modelled, photonic crystal, thin-film, GaAs solar cells with PhC on top. The efficiency of this solar cell, using the photonic crystal, was improved by 6.3% over the efficiency of this same solar cell without PhC. Thus, our research strongly suggests that the unique properties of the photonic crystal could be used as a new generation of ARC.

Optoelectronic performance of a modified nanopyramid solar cell

The optical and electrical characteristics of modified nanopyramid grating silicon solar cells (SCs) are numerically reported and analyzed. The modified grating SC consists of an upper tapered nanopyramid and lower nanorectangular parts. The geometrical parameters of the proposed design are tuned to maximize the optical absorption and hence the ultimate efficiency. The finite-difference time-domain and finite-element methods are utilized via Lumerical software packages for studying the optoelectronics performance of the suggested design. In this investigation, short-circuit current density (Jsc), optical generation rate, open-circuit voltage (Voc), electrical fill factor, and electrical power conversion efficiency (PCE) are calculated thoroughly. Moreover, the effects of the doping concentration and carrier lifetime on the device performance are also studied. The modified design provides an optical ultimate efficiency of 40.93% and optical Jsc of 33.49 mA/cm2, respectively, with an improvement of 28.3% over the conventional nanopyramid SC. This enhancement is due to the ability of the grating sidewalls to trap more light through the active layer. Additionally, the spacing between the adjacent nanopyramid structures can exhibit microcavity resonance, which contributes to light broadband absorption improvement. The p-i-n axial doping of the suggested SC exhibits Voc of 0.57 V, Jsc of 28.42 mA/cm2, and PCE of 13.3%, which are better than the Voc of 0.559 V, Jsc of 19.6 mA/cm2, and PCE of 8.95% of a conventional nanopyramid SC.