Silicon micro-structure and ZnO nanowire hierarchical assortments for light management

Choudhury, Bikash Dev; Abedin, Ahmad; Dev, Apurba; Sanatinia, Reza; Anand, Srinivasan

doi:10.1364/ome.3.001039

Cited by 26 publications

(16 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As previously described, KOH‐etching is a simple method for producing microarrays of pyramids in silicon (100) that reduce its specular reflectance, but the pyramids vary in size, making the structures aperiodic. Fabricating periodic pyramidal microarrays of varying geometries is possible but requires several extra patterning steps . Thus, to evaluate what potential benefits may be gained by tuning the periodicity of microarrays, we simulated pseudo‐aperiodic microarrays and compared their reflectance against our simulation results from periodic microarrays discussed earlier consisting of triangles whose width and height are both 5 µm.…”

Section: Resultsmentioning

confidence: 99%

“…Though a number of hierarchical antireflective structures have been demonstrated, general guidelines for the design parameters of hierarchical structures to attain desired antireflective properties are still lacking. We explored the parameter space of hierarchical structures to synthesize a set of guidelines relating how their structural parameters affect various aspects of their reflectivity, including the type of reflectivity (e.g., specular, diffuse, hemispherical), its spectral response, and its angle‐dependency, across the solar spectrum (250–2500 nm).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Design Rules for Tailoring Antireflection Properties of Hierarchical Optical Structures

León

Hiszpanski

Bond

et al. 2017

Advanced Optical Materials

View full text Add to dashboard Cite

Hierarchical structures consisting of small sub‐wavelength features stacked atop larger structures have been demonstrated as an effective means of reducing the reflectance of surfaces. However, optical devices require different antireflective properties depending on the application, and general unifying guidelines on hierarchical structures' design to attain a desired antireflection spectral response are still lacking. The type of reflectivity (diffuse, specular, or total/hemispherical) and its angular‐ and spectral‐dependence are all dictated by the structural parameters. Through computational and experimental studies, guidelines have been devised to modify these various aspects of reflectivity across the solar spectrum by proper selection of the features of hierarchical structures. In this wavelength regime, micrometer‐scale substructures dictate the long‐wavelength spectral response and effectively reduce specular reflectance, whereas nanometer‐scale substructures dictate primarily the visible wavelength spectral response and reduce diffuse reflectance. Coupling structures having these two length scales into hierarchical arrays impressively reduces surfaces' hemispherical reflectance across a broad spectrum of wavelengths and angles. Such hierarchical structures in silicon are demonstrated having an average total reflectance across the solar spectrum of 1.1% (average weighted reflectance of 1% in the 280–2500 nm range of the AM 1.5 G spectrum) and specular reflectance <1% even at angles of incidence as high as 67°.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Design Rules for Tailoring Antireflection Properties of Hierarchical Optical Structures

León

Hiszpanski

Bond

et al. 2017

Advanced Optical Materials

View full text Add to dashboard Cite

show abstract

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14] Here, a sol-gel method has been developed and used for the fabrication of (relatively) thick porous polycrystalline ZnO layers. A similar method has already been reported for thin films by, e.g., Gohdsi et al 34 and Choudhury et al 44 Here the method has been extended for obtaining well-defined thick ZnO films (up to ∼2 μm) by using a sequential drop-cast approach in a 'vacuum' environment. The 'building' of these sequential ZnO layers to one thick layer provides a method to tune specific layer thicknesses on the micro/nanoscale.…”

mentioning

confidence: 84%

Investigations of Sol-Gel ZnO Films Nanostructured by Reactive Ion Beam Etching for Broadband Anti-Reflection

Visser

Prajapati

et al. 2017

ECS J. Solid State Sci. Technol.

Self Cite

View full text Add to dashboard Cite

A novel ZnO dry etching approach is introduced using reactive ion beam etching of thick sol-gel ZnO layers for controlled nanodisk/nanocone array fabrication. In this approach the same system can be used for the colloidal lithography mask (silica particles) size reduction by a fluorine-based chemistry and etching of the ZnO nanostructures by a CH 4 /H 2 /Ar chemistry. This resulted in a ZnO:SiO 2 etch selectivity of ∼3.4 and etch rate of ∼56 nm/min. Thick sol-gel ZnO layers, nanodisk arrays and (truncated) nanocone arrays were fabricated and their optical properties analyzed by finite-difference time-domain simulations and spectrally-resolved total/specular reflectivity measurements. The demonstrated broadband omnidirectional anti-reflection, controlled nanostructure period/geometry and low absorption in the visible-NIR spectrum makes these sol-gel ZnO nanostructures very interesting for many optoelectronic applications, including photovoltaics. ZnO is a wide bandgap (∼3.37 eV at room temperature) II-VI semiconductor. Predominantly it crystalizes in the Wurtzite crystal structure and bulk ZnO has a refractive index of n ≈ 1.9-2.2 in the NIR-visible wavelength range. Some of the features of ZnO interesting for photovoltaic applications are its high transparency in the visible-NIR spectrum, a wide bandgap, a large exciton binding energy (60 meV at room temperature), non-centrosymmetric structure, strong room temperature luminescence and biocompatibility. 1,2ZnO has been studied extensively as a candidate for a number of applications, e.g., transparent conductive electrodes, optical waveguides, piezo-electric transducers, acoustic wave devices, conductive gas sensors, solar cell windows and biosensing. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] Here, a sol-gel method has been developed and used for the fabrication of (relatively) thick porous polycrystalline ZnO layers. A similar method has already been reported for thin films by, e.g., Gohdsi et al. 34 and Choudhury et al. 44 Here the method has been extended for obtaining well-defined thick ZnO films (up to ∼2 μm) by using a sequential drop-cast approach in a 'vacuum' environment. The 'building' of these sequential ZnO layers to one thick layer provides a method to tune specific layer thicknesses on the micro/nanoscale. Other approaches for obtaining thick porous ZnO layers have been reported. [45][46][47] The sol-gel method is attractive since it is simple, cheap and straight forward. In addition, this method offers the flexibility to provide ZnO layers on a variety of surfaces. Sol-gel layers, consisting of crystals with c-axis orientation vertical to the surface, can be * Electrochemical Society Member.z E-mail: dvisser@kth.se obtained when the substrate material has a similar Wurtzite crystal structure to ZnO, e.g., GaN, SiC and (0001)-sapphire. For other types of substrates dense sol-gel layers, composed of non-specific direction, can still be obtained. In this work, thick ZnO layers have been fabricated and nanostructured on a Si substrate. These laye...

show abstract

“…2(a). The diameter of and the spacing between the etched pillars are predominantly determined by the silica (mask) particle size and the open space between the particles [22].…”

Section: Fabrication Of Si Nanopillars With a Sio2 Over-layermentioning

confidence: 99%

Silicon nanopillar arrays with SiO_2 overlayer for biosensing application

Choudhury¹,

Casquel²,

Bañuls³

et al. 2014

Opt. Mater. Express

Self Cite

View full text Add to dashboard Cite

Abstract:We present the fabrication of silicon dioxide (SiO 2 ) coated silicon nanopillar array structures and demonstrate their application as sensitive optical biosensors. Colloidal lithography, plasma dry etching and deposition processes are used to fabricate SiO 2 coated Si nanopillar arrays with two different diameters and periods. Proof of concept bio recognition experiments are carried out with the bovine serum albumin (BSA)/antiBSA model system using Fourier transform visible and IR spectrometry (FT-VIS-IR) in reflection mode. A limit of detection (LoD) value of 5.2 ng/ml is estimated taking in to account the wavenumber uncertainty in the measurements.

show abstract

Silicon micro-structure and ZnO nanowire hierarchical assortments for light management

Cited by 26 publications

References 26 publications

Design Rules for Tailoring Antireflection Properties of Hierarchical Optical Structures

Design Rules for Tailoring Antireflection Properties of Hierarchical Optical Structures

Investigations of Sol-Gel ZnO Films Nanostructured by Reactive Ion Beam Etching for Broadband Anti-Reflection

Silicon nanopillar arrays with SiO_2 overlayer for biosensing application

Contact Info

Product

Resources

About