Fabrication Of 3D Photonic Crystals Research Articles

Cross‐Sectional Investigation of Multihigh‐Energy Proton‐Implanted Single Crystalline Diamond

Comprehending the implantation‐related characteristic quantities of multihigh‐energy proton irradiation of diamond is of significant technological interest for sensing applications, fabrication of 3D photonic crystals, and color centers (e.g., NV− center)‐based quantum computing. Herein, proton‐projected ranges and defect distributions in the (010) plane (Y‐normal plane) of microwave plasma chemical vapor deposition (MPCVD)‐grown diamond irradiated with 0.5–2.0 MeV proton (H+ or molecular ions) in a nonchanneling (near [001], Z‐axis) direction, are experimentally measured via cross‐sectional optical microscopy and high‐resolution confocal Raman spectroscopy mapping. It is found that the projected ranges of the experimental findings and the simulation results indicate good consistencies, whereas there is considerable disagreement between them in regards to longitudinal straggling and lateral straggling. Based on the comparisons and analyses, a clear view of protons implanted in single crystalline diamond in the high‐energy range theoretically and experimentally is obtained.

Rapid and Large‐Scale Fabrication of Full Color Woodpile Photonic Crystals via Interference from a Conformal Multilevel Phase Mask

AbstractThe practical use of photonic crystals with structural colors requires technology capable of rapidly producing large‐area, three‐dimensional (3D) periodic nanostructures. Until now, the fabrication of 3D photonic crystals has relied mainly on additive manufacturing and colloidal self‐assembly. These technologies have provided a useful academic platform based on precisely controlled 3D periodicity but have not evolved into mass production technology. Here, optical lithography for the rapid fabrication of large‐area 3D photonic crystals with structural colors is introduced. The key strategy is to incorporate two orthogonal line gratings (periodicity: 300 nm) made of an elastomer to create a conformal multilevel phase mask. When the mask is irradiated with a 355 nm laser, the five beam interference is established in the proximity region. The interlayer thickness between the two orthogonal line gratings controls the phase difference, which is closely related to the symmetry of the resulting 3D interference pattern. The interlayer thickness is designed to produce a woodpile structure with a planar periodicity of 300 nm and a vertical periodicity of 716 nm. The pattern area of the woodpile photonic crystal is expanded to 1 in2. Red, green, and blue colors are experimentally realized by controlling the vertical shrinkage of the photoresist.

Three-dimensional photonic crystal simultaneously integrating a nanocavity laser and waveguides

Three-dimensional (3D) integration of photonic devices is an ultimate route toward highly integrated photonic circuits. 3D photonic crystals (PCs) are a promising platform for 3D integration because of their complete photonic bandgaps (cPBGs) which enables full control of light. However, simultaneous integration of active and passive devices into a 3D PC has been hindered due to fabrication difficulties. Here, we simultaneously integrate a nanocavity laser and waveguides into a 3D PC with a cPBG at near-IR wavelengths using micromanipulation technology. The proposed plate-insertion stacking method allowed fabrication of 3D PCs with a large number of layers, enabling integration of the active and passive circuit components. Laser emission from the photo-excited nanocavity laser was observed from the output port of the waveguides, demonstrating successful guiding of the light from the nanocavity laser in the 3D PC. This work paves the way for 3D photonic circuits using 3D PCs with cPBGs.

Large scale fabrication of asymmetric 2D and 3D micro/nano array pattern structures using multi-beam interference lithography technique for Solar cell texturing application

A method for the large scale fabrication of nano/micro array patterned structure for solar Photovoltaics (PV) is demonstrated by the use of laser interference lithography (LIL) technique. Since micro/nano array patterned structures for photonic arrangement are of increasing importance in higher efficiency solar PV cell concepts, structuring technique and miniaturization in size play a vital role in their realization/fabrication. In this paper, we have designed and modelled multi-beam interference lithography technique (MBIL) for the fabrication of solar PV cells. The generated periodic 1D, 2D and 3D micro/nano array structures are done using MATLAB. The obtained results show that the complexity of the pattern structures varies with the variation in position of beams and angle of incidence. The interference parameters such as wavelength, slit separation, distance between slit and screen influence in generation of periodic array pattern structures. The maximum intensity occurs at an angle of incidence 45 degree. The obtained pattern structures have the periodicity of 0.19 µm for 1064 nm, 0.18 µm for 1024 nm, 0.14 µm for 780 nm, 0.12 µm for 650 nm and 0.07 µm for 565 nm. Depth of the focus is found to be 0.029 µm for 1064 nm, 0.028 µm for 1024 nm, 0.024 µm for 780 nm, 0.020 µm for 650 nm and 0.015 µm for 565 nm. MBIL can be applied in fabrication of 3D photonic crystals, magnetic storage, solar cells, waveguides, calibration grids, Organic Light Emitting Diodes (OLEDs) and functional surfaces of sensors.

Fabrication of 3D Photonic Crystals toward Arbitrary Manipulation of Photons in Three Dimensions

The creation of large-area, unintentional-defect-free three-dimensional (3D) photonic crystals in the optical regime is a key challenge toward the realization of the arbitrary 3D manipulation of photons. In this article, we discuss an advanced fabrication method of 3D silicon photonic crystals based on the highly accurate alignment and wafer bonding of silicon-on-insulator (SOI) wafers. We introduce an advanced alignment system, in which the alignment process is automated by image recognition and feed-back control of stages, and show that it achieves an alignment accuracy better than ~50 nm. The bonding of SOI wafers is also investigated to obtain 3D crystals composed of highly pure crystalline silicon. We show the fabrication results of large-area 3D photonic crystals based on such considerations and demonstrate the successful introduction of artificial defects as functional components, such as coupled waveguide pairs or waveguides/nanocavities. We expect that these will be pioneering results toward the arbitrary 3D control of photons using 3D photonic crystals.

Fabrication of Photonic Crystal Based on Polystyrene Particles

Photonic crystals are dielectric materials with different refractive index or permittivity periodically. Photonic crystals have widely application for future technology such as waveguide, optical transistor, cavity of laser and biosensor. Photonic crystals can be fabricated in three types i.e 1D, 2D and 3D structure. In this paper, we report the successful fabrication of 3D photonic crystal from polystyrene particles. The fabrication process began with the synthesis of polystyrene particles followed by deposition on glass and flexible substrate using self-assembly method. We obtained polystyrene monodispered particles which have a uniform shaped with diameter 320 nm. Self-assembly method resulted to the arrangement of polystyrene particles on glass and flexible substrate. Stop band which is related to its optical property are at wavelength of 721 nm and 631 nm for photonic crystal on glass and flexible substrate, respectively. We found that filling fraction of photonic crystal on flexible substrate is lower than that of glass substrate due to some defects.

Three-dimensional photonic crystals fabricated by simultaneous multidirectional etching

We discuss three-dimensional (3D) photonic crystals fabricated by simultaneous multidirectional plasma etching. First, we investigate a method for controlling the ion sheath used in reactive ion etching for obtaining multidirectional etching. We then discuss the fabrication tolerance from an analytical perspective. Based on our results, we demonstrate the fabrication of 3D photonic crystals with thicknesses of 1, 1.5, and 2 lattice periods in the surface-normal direction on single-crystalline silicon wafers, which show high reflectance $(\ensuremath{\sim}100%)$ and low transmittance $(\ensuremath{-}17\phantom{\rule{0.28em}{0ex}}\mathrm{dB})$ at optical communication wavelengths, suggesting the formation of a complete photonic band gap. We reveal that the shape of the etched holes limits the performance of 3D photonic crystals and suggest possible ways to improve the band-gap effect. Moreover, we show that 3D photonic crystals with short lattice constants show high reflectance $(\ensuremath{\sim}80%)$ at visible to near-infrared wavelengths. By investigating the influence of absorption on the characteristics of 3D photonic crystals, we reveal that the reflectance remains as high as 94% in the photonic band-gap range even when the absorption of silicon is taken into account. We find that a unique increase of absorption occurs at several discrete wavelengths below the photonic band gap, suggesting the possibility of manipulating light absorption. These results not only simplify the fabrication of 3D photonic crystals, but also provide a basis for realizing 3D photonic nanostructures that include other materials.

Fabrication of 3D Photonic Crystals from Chitosan That Are Responsive to Organic Solvents

Inspired by photonic nanostructures in nature, such as the hair-like chaetae on the body of sea mice, inverse opal photonic crystals films were fabricated with chitosan, a kind of biomacromolecule found in nature. First, monodispersed polystyrene (PS) colloidal crystal templates with different particle sizes were prepared. The inverse opal films (IOFs) were fabricated through in situ cross-linking of the PS templates. The IOFs contain periodically ordered interconnecting pores that endow the films with photonic stop bands and structural colors, which are visible to the naked eye. The IOFs exhibit rapid reversible changes in their structural colors and reflectance peaks in response to alcohols and phenols. Possible mechanisms for the shifts in the IOF's reflectance peaks are proposed. The changes in the IOFs in response to alcohols and phenols provide a potential way to visually detect these organic solvents.

Holographic fabrication of 3D photonic crystals through interference of multi-beams with 4 + 1, 5 + 1 and 6 + 1 configurations.

In this paper, we are able to fabricate 3D photonic crystals or quasi-crystals through single beam and single optical element based holographic lithography. The reflective optical elements are used to generate multiple side beams with s-polarization and one central beam with circular polarization which in turn are used for interference based holographic lithography without the need of any other bulk optics. These optical elements have been used to fabricate 3D photonic crystals with 4, 5 or 6-fold symmetry. A good agreement has been observed between fabricated holographic structures and simulated interference patterns.

Fabrication of high aspect ratio microtube arrays for 2D photonic crystals

This paper describes the fabrication of 2D photonic crystals made of high aspect ratio Si microtube arrays. The tube fabrication is based on the creation of macropore arrays in n-doped Si substrates via photoassisted electrochemical etching. These macropores are successively filled using thermal oxidation and chemical vapor depostion. The substrate material is partially removed by a KOH immersion, and the filled macropores are exposed, forming arrays of microtubes with very high aspect ratios of up to 1:60. Point and line defects are introduced into some of the tube arrays by selectively omitting macropores during the fabrication. The mechanical properties of the tubes were investigated by measuring their stiffness and elastic modulus using an atomic force microscope based setup. Additionally, the resonant modes of the microtubes were simulated with FEM methods. Optical simulations reveal that these tube arrays form 2D photonic crystals, which can contain bandgaps for TM polarized light. It is also shown that the optical properties of the photonic crystals depend strongly on the tube filling factor. Adjusting the filling factor of the tubes allows tuning of the photonic properties of the tube arrays.

Creating bio-inspired hierarchical 3D–2D photonic stacks via planar lithography on self-assembled inverse opals

Structural hierarchy and complex 3D architecture are characteristics of biological photonic designs that are challenging to reproduce in synthetic materials. Top–down lithography allows for designer patterning of arbitrary shapes, but is largely restricted to planar 2D structures. Self-assembly techniques facilitate easy fabrication of 3D photonic crystals, but controllable defect-integration is difficult. In this paper we combine the advantages of top–down and bottom–up fabrication, developing two techniques to deposit 2D-lithographically-patterned planar layers on top of or in between inverse-opal 3D photonic crystals and creating hierarchical structures that resemble the architecture of the bright green wing scales of the butterfly, Parides sesostris. These fabrication procedures, combining advantages of both top–down and bottom–up fabrication, may prove useful in the development of omnidirectional coloration elements and 3D–2D photonic crystal devices.

Fabrication of 3D Photonic Crystals of Non-Magnetic Ellipsoids with Different Aspect Ratio

This paper introduces a method of preparation of photonic crystals with non-magnetic ellipsoid as building blocks. Under the condition of above its glass-transition temperature, monodispersed polystyrene (PS) spheres with the diameter of 260 nm and 360 nm were respectively elastic stretched by applying external force with different values to get different ellipsoids with different aspect ratios. The assembly procedure was carried out by applying the vertical deposition self-assembly method in a magnetic field under the guidance of magnetic fluids. In this paper, We report the crystalline structure with long range order.

Design, optimization and fabrication of 2D photonic crystals for solar cells

This paper presents the optimization of 2D photonic crystals (PCs) onto Si wafers to improve the performance of c-Si PV cells. The objective is to find a structure capable of minimizing the reflectance of the Si wafer in the spectral range between 400nm and 1000nm. The study has been limited to PCs that can be fabricated and characterized with the tools and technology available and to dimensions in the same order as the visible light wavelength. PCs with different shapes and dimensions have been simulated and finally the optimum structure has been fabricated by a process based on laser interference lithography (LIL) and reactive ion etching (RIE). This optimized PC presents an average reflectance of 3.6% in the selected wavelength range, without any other material used as antireflective coating. This result means a drastic reduction in comparison with reflectance obtained out of the standard wet etch texturization used in current solar cell manufacturing lines.

2D Periodic Gratings by Laser Processing

As the thickness of crystalline silicon wafers for use in solar cells is reduced, transmission-related losses become increasingly important. Very thin silicon solar cells will benefit from surface structures exhibiting efficient light trapping, such as 2D periodic structures with diffractive properties. Furthermore, multicrystalline silicon solar cells will benefit from a front surface texture which exhibits lower reflectance than the standard iso-etch. In this paper, we investigate three new methods for creating such structures based on the formation of a 2D periodic template from a colloidal suspension of microspheres and subsequent laser processing and etching.Polystyrene spheres with 1μm diameter are spin-coated onto a silicon wafer, and forms a hexagonal pattern through self-ordering. The wafer is irradiated with an ultrashort-pulse laser with sufficient power to form pits in the wafer surface below the individual polystyrene spheres, thus transferring the hexagonal pattern to the silicon wafer. The maximum obtained diameter and depth of the pits are 600nm and 100nm respectively.To increase the depth of the pits we deposit the self-ordering microspheres on a silicon nitride etch barrier, followed by laser irradiation for local opening of the barrier and an isotropic etch through these holes. With this approach we are able to create structures with a base diameter of 800nm and a depth of 350nm. These structures are found in simulations to have good light-trapping properties and the method may therefore be suitable for the fabrication of 2D photonic crystals for light-trapping in silicon solar cells.

Fabrication of 2D photonic crystals using block copolymer patterns on as grown LEDs

Di-block copolymer polystyrene-block-polymethyl methacrylate (PS-b-PMMA) was used to make patterns over a large area of as grown LEDs. The polymer patterns on LEDs surface could be transferred to the underlying p-GaN, the topmost layer of as grown LEDs by both reactive ion etching (RIE) and photo-enhanced chemical (PEC) etching. Removal of remaining polymer chains results in patterned LEDs which shows higher light extraction efficiency. In our experiment, much higher intensity for patterned LEDs in both photoluminescence (PL) and electroluminescence (EL) data plot were found. Similar improvements were found in I–V and L–I curves for patterned LEDs.

Fabrication of 3D Photonic Crystals of Ellipsoids: Convective Self‐Assembly in Magnetic Field

Three-dimensional photonic crystals of ellipsoidal colloidal particles are prepared by direct convective self-assembly from suspension with the aid of a magnet. The magnetic field provides the orientational order, which is additionally needed for these colloidal particles with symmetry lower than spherical. The positional order is provided by the convection, just as for spherical colloids.

Fabrication of 3D-photonic crystals via UV-nanoimprint lithography

Optical lithography will reach its limits due to the diffraction effects encountered and the necessity for using complex resolution enhancement techniques like optical proximity correction, phase shift masks, and off-axis illumination [L. W. Liebmann et al., in Advanced Semiconductor Lithography (2001), Vol. 45]. The restrictions on wavelength, in combination with high process and equipment costs, make low-cost, simple imprinting techniques competitive with next-generation lithography methods. There are several nanoimprint lithography (NIL) techniques which can be categorized depending on the process parameters and the imprinting method—either step and repeat or full wafer single-step imprinting. A variety of potential applications has been demonstrated using NIL (e.g., surface acoustic wave devices, vias and contact layers with dual damascene imprinting process, Bragg structures, patterned media) [M. D. Stewart et al., Proc. SPIE 5751, 210 (2005); P. Dorsey et al., in Discrete Track Recording (DTR) Media Fabricated using Nanoimprint Lithography, NNT 1–3 December (2004)]. In this work UV-NIL has been selected for the fabrication process of 3D-photonic crystals.

Triply Periodic Bicontinuous Structures as Templates for Photonic Crystals: A Pinch‐off Problem

Triply periodic diamond, cubic, and gyroid structures are studied as templates for the fabrication of 3D photonic crystals (see figure). The achievable backfilling volume fraction and bandgap properties are analyzed by considering the pinch-off of level surfaces. The conformal coating on such templates is found to result in incomplete filling and loss of the photonic bandgap. An attempt to solve this problem is made by using electrophoretic deposition, which results in a nearly completely filled 3D titania structure. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2089/2007/c0147_s.pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Defect Engineering in Self-Assembled 3D Photonic Crystals

This work describes the combination of photolithography and self-assembly methods for fabrication of 3D photonic crystals (PCs) with well-defined micron-scale line defects embedded in the PCs. Line defects with different dimensions, shapes, and compositions have been introduced into the 3D PCs by choosing different photoresists, masks, and template-directed assembly techniques. Infiltration of carbon using high-temperature chemical vapor deposition (CVD) technique showed that the fabrication procedure offers an ideal approach to functional 3D photonic devices from self-assembled photonic crystals.

Defect Engineering in Self-Assembled 3D Photonic Crystals

This work describes the combination of photolithography and self-assembly methods for fabrication of 3D photonic crystals (PCs) with well-defined micron-scale line defects embedded in the PCs. Line defects with different dimensions, shapes, and compositions have been introduced into the 3D PCs by choosing different photoresists, masks, and template-directed assembly techniques. Infiltration of carbon using high-temperature chemical vapor deposition (CVD) technique showed that the fabrication procedure offers an ideal approach to functional 3D photonic devices from self-assembled photonic crystals.