Optical shortpass filters based on macroporous silicon

Lehmann, Volker; Stengl, R.; Reisinger, H.; Detemple, Ralf; Theiß, W.

doi:10.1063/1.1334943

Cited by 81 publications

(32 citation statements)

References 3 publications

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“…͓DOI: 10.1063/1.2137688͔ Porous silicon, 1,2 and in particular, macroporous silicon, 3,4 has attracted a lot of attention as a unique possibility to structure silicon. 5 This material system has been applied to optical shortpass filters 6 as well as to twodimensional ͑2D͒ and three-dimensional ͑3D͒ photonic crystals. 7,8 All these applications depend on the uniformity of the porous material.…”

mentioning

confidence: 99%

Controlled nonuniformity in macroporous silicon pore growth

Matthias¹,

Müller²,

Gösele³

2005

Applied Physics Letters

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Photoelectrochemical etching of uniform prestructured silicon wafers in hydrofluoric acid containing solutions yields periodic structures that can be applied to two-and three-dimensional photonic crystals or microfluidics. Here we demonstrate experimentally macroporous silicon etching initiated by a nonuniform predefined lattice. For conveniently chosen parameters we observe a stable growth of pores whose geometrical appearance depends strongly on the spatially different nucleation conditions. Moreover, we show preliminary results on three-dimensionally shaped pores. This material can be used to realize hybrid photonic crystal structures and incorporate waveguides in three-dimensional photonic crystals. © 2005 American Institute of Physics. ͓DOI: 10.1063/1.2137688͔ Porous silicon, 1,2 and in particular, macroporous silicon, 3,4 has attracted a lot of attention as a unique possibility to structure silicon. 5 This material system has been applied to optical shortpass filters 6 as well as to twodimensional ͑2D͒ and three-dimensional ͑3D͒ photonic crystals. 7,8 All these applications depend on the uniformity of the porous material. This property results from the perfect, lithographically arranged, uniform inverted pyramids acting as nuclei for the pore growth and the self-stabilized photoelectrochemical etching process used. The so-manufactured 3D photonic crystals show complete band gaps of about 5%. Recently, we proposed large 3D photonic band gaps in diamondlike structures, which may be fabricated using complex structured silicon wafers. 9 Here we present a detailed investigation focused on spatially different nucleation conditions. A simple quadratic lattice with a basis of two nonequally sized inverted pyramids is defined. We will demonstrate under which experimental conditions a stable pore growth is observed. Moreover, the nonequally sized nuclei result in a significant initial offset in height between adjacent pores. We will answer the question of how this considerable difference is affected by the selfstabilized interaction between the pores. This approach is well suited to incorporate air defects in photonic band-gap materials in two and three dimensions acting as resonators or waveguides. In particular, this is a step towards the experimental realization of the predicted 2D photonic crystal hybrid structures suggested by Trifonov et al. 10 Typically macroporous silicon is grown in a photoelectrochemical etching process. 5 An arbitrary 2D lattice is defined lithographically on the ͑100͒-oriented n-type silicon wafer. A subsequent anisotropic etching in potassium hydroxide ͑KOH͒ forms inverted pyramids acting as nuclei for the pore growth. This structured frontside is exposed to hydrofluoric acid ͑HF͒. Illuminating the backside of the silicon wafer generates electron-hole pairs. The electrons are extracted by the applied anodic bias whereas the electronic holes-the minority charge carriers-diffuse through the whole wafer to the silicon electrolyte interface. Due to the depletion layer at this interface an e...

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confidence: 99%

Controlled nonuniformity in macroporous silicon pore growth

Matthias¹,

Müller²,

Gösele³

2005

Applied Physics Letters

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“…Dye-doped polymer filters offer wide and deep rejection, but thermal and environmental stability is a big concern, and the control of the position and shape of the pass band is also not straightforward. Ultraviolet filters based on MPSi were proposed recently [6,16,17] as an attractive alternative to the existed technology. Such filters utilize the leaky waveguide transmission through the pores in MPSi material.…”

Section: Macroporous Silicon Uv Filtersmentioning

confidence: 99%

“…Comparatively little work has been done concerning the propagation of light in pore direction, in particular for geometrically well-defined arrays of straight pores with large aspect ratios. In [6] it was shown that uniform and ordered arrays of straight macropores with diameters in the 1 µm region and lengths of several 100 µm act as efficient short pass filters in the blue to UV region. Here we will present and summarize new results on wave propagation along pores in a variety of structures.…”

Section: Introductionmentioning

confidence: 99%

Commercial applications of porous Si: optical filters and components

Kochergin

Foell²

2007

Phys. Status Solidi (c)

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It is shown that porous Silicon in various geometries and morphologies can be used for novel optical elements by combining theoretical insights with suitable porous structures and some pre-and post-processing of the Silicon. The paper restricts itself to light propagation in the pore direction. Theoretical and experimental results will be presented for the following novel optical elements: environmentally stable optical components from mesoporous Silicon, long wave pass filters, macroporous Silicon UV Filters, and polarization components for the UV range. Either new components are presented, mostly with first experimental results, or the state-of-the art for previously discussed elements is considerably improved upon.

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“…Multistructured porous silicons (PSi) such as distributed Bragg reflectors (DBR) PSi and Rugate PSi have been a topic of interest, because of their use in chemical and biological sensors, biomaterials, and optical devices [1][2][3][4] . They exhibit unique optical properties providing the reflection of a specific wavelength in the optical reflectivity spectrum and are an attractive candidate for building nanostructured composite materials [5] .…”

Section: Introductionmentioning

confidence: 99%

“…They exhibit unique optical properties providing the reflection of a specific wavelength in the optical reflectivity spectrum and are an attractive candidate for building nanostructured composite materials [5] . DBR PSi is typically prepared by an applying a computer-generated pseudo-square current waveform to the etch cell which results two distinct indices and exhibits photonic structure of Bragg filters [6][7][8][9][10] . Rugate-structured porous silicon having photonic structure of rugate filter in which refractive index varies sinusoidally has been recently developed by applying a computer-generated pseudo-sinusoidal current waveform [11] .…”

Section: Introductionmentioning

confidence: 99%

Investigation of Relationship between Reflection Resonance and Applied Current Density in Bragg Photonic Crystal

Kim¹

2012

Journal of the Chosun Natural Science

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Relationship between reflection resonance and applied current density in Bragg photonic crystal has been investigated. Multiple bit encodes of distributed Bragg reflector features have been prepared by electrochemical etching of crystalline silicon by using various square wave current densities. Optical characterization of multi-encoding of distributed Bragg reflectors on porous silicon was achieved by Ocean optics 2000 spectrometer for the search of possible applications of multiple bit encoding of distributed Bragg reflectors such as multiplexed assays and chemical sensors. The morphology and cross-sectional structure of multi-encoded distributed Bragg reflectors was investigated by field emission scanning electron micrograph.

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Optical shortpass filters based on macroporous silicon

Cited by 81 publications

References 3 publications

Controlled nonuniformity in macroporous silicon pore growth

Controlled nonuniformity in macroporous silicon pore growth

Commercial applications of porous Si: optical filters and components

Investigation of Relationship between Reflection Resonance and Applied Current Density in Bragg Photonic Crystal

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