Large‐Area Three‐Dimensional Structuring by Electrochemical Etching and Lithography

Matthias, Sven; Müller, Frank; Jamois, Cécile; Wehrspohn, Ralf B.; Gösele, U.

doi:10.1002/adma.200400436

Cited by 126 publications

(85 citation statements)

References 33 publications

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“…Three-dimensional macroporous structures behave as photonic crystals [21,22], and exhibit interesting thermal emission characteristics [26][27][28]; however, they are not good candidates for TPV applications since it is very difficult to efficiently reduce thermal emission at large wavelength bands [28]. In order to take advantage of the good thermal stability of crystalline silicon 3D structures we decided to deposit a conformal thin metal layer over the structure.…”

Section: Sample Fabricationmentioning

confidence: 99%

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Three-dimensional metallo-dielectric selective thermal emitters with high-temperature stability for thermophotovoltaic applications

Garín

Hernández

Trifonov

et al. 2015

Solar Energy Materials and Solar Cells

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Selective thermal emitters concentrate most of their spontaneous emission in a spectral band much narrower than a blackbody. When used in a thermophovoltaic energy conversion system, they become key elements defining both its overall system efficiency and output power. Selective emitters' radiation spectra must be designed to match their accompanying photocell's band gap and, simultaneously, withstand high temperatures (above 1000 K) for long operation times. The advent of nanophotonics has allowed the engineering of very selective emitters and absorbers; however, thermal stability remains a challenge since 1 of 22 nanostructures become unstable at temperatures much below the melting point of the used materials. In this paper we explore an hybrid 3D dielectric-metallic structure that combines the higher thermal stability of a monocrystalline 3D Silicon scaffold with the optical properties of a thin Platinum film conformally deposited on top. We show experimentally that these structures exhibit a selective emission spectrum suitable for TPV applications and that they are thermally stable at temperatures up to 1100 K. These structures are ideal in combination with III-V semiconductors in the range Eg=0.4-0.55 eV such as InGaAsSb (Eg=0.5-0.6 eV) and InAsSbP (Eg=0.3-0.55 eV).

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Section: Sample Fabricationmentioning

confidence: 99%

“…Finally, the pore walls were widened isotropically through consecutive dry-oxidation/oxideremoval steps (fig 1c,1d) until the points of maximum diameter connected laterally (fig 1e), creating the 3D cubic symmetry [22] (fig 1f). On each step, a SiO2 layer of 100nm was grown in a tube furnace with a 70 min.…”

Section: Sample Fabricationmentioning

confidence: 99%

Three-dimensional metallo-dielectric selective thermal emitters with high-temperature stability for thermophotovoltaic applications

Garín

Hernández

Trifonov

et al. 2015

Solar Energy Materials and Solar Cells

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“…First, the introduction of arbitrarily shaped defects presents an unresolved problem. Second, structures created this way show at best a very narrow cPBG [40] unless the process is combined with focused-ion-beam milling of channels, [41] which significantly reduces the simplicity of this method. …”

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Introducing Defects in 3D Photonic Crystals: State of the Art

2006

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Public Reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comment regarding this burden estimates or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302, and to the Office of Management and Budget, Paperwork Reduction Project (0704-0188,) Washington, DC 20503. AGENCY USE ONLY ( Leave Blank)2. REPORT DATE Advanced Materials, 18, 2665-2678 (2006). 3D photonic crystals (PhCs) and photonic bandgap (PBG) materials have attracted considerable scientific and technological interest. In order to provide functionality to PhCs, the introduction of controlled defects is necessary; the importance of defects in PhCs is comparable to that of dopants in semiconductors. Over the past few years, significant advances have been achieved through a diverse set of fabrication techniques. While for some routes to 3D PhCs, such as conventional lithography, the incorporation of defects is relatively straightforward; other methods, for example, selfassembly of colloidal crystals (CCs) or holography, require new external methods for defect incorporation. In this review, we will cover the state of the art in the design and fabrication of defects within 3D PhCs. The figure displays a fluorescence laser scanning confocal microscopy image of a y-splitter defect formed through two-photon polymerization within a CC. SUBJECT TERMS 15. NUMBER OF PAGES 1416. PRICE CODE SECURITY CLASSIFICATION OR REPORT UNCLASSIFIED SECURITY CLASSIFICATION ON THIS PAGE UNCLASSIFIED SECURITY CLASSIFICATION OF ABSTRACT UNCLASSIFIED LIMITATION OF ABSTRACT UL IntroductionPhotonic crystals (PhCs) are materials that possess spatial periodicity in their dielectric constant on the order of the wavelength (k) of light. These materials can strongly modulate light [1] and, with sufficient dielectric contrast and an appropriate geometry, may exhibit a photonic bandgap (PBG). This concept was first proposed in 1975 by Bykov [2] but remained relatively unknown until the seminal work of Yablonovitch [3] and John. [4] In a rough analogy to semiconductors, which possess an electronic bandgap, a PBG material prohibits the existence of photons with energies in the PBG. PhCs are naturally classified by the dimensionality of their periodicity, and in order to rigorously prevent the propagation of PBG frequencies in all directions, a 3D PhC with an omnidirectional, or complete PBG (cPBG) is required. cPBG materials have been fabricated and well characterized for operation at microwave and radio frequencies, however, operation in the visible and IR requires the characteristic length scales of these structures to be scaled down by several orders of magnitude...

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“…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.…”

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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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Large‐Area Three‐Dimensional Structuring by Electrochemical Etching and Lithography

Cited by 126 publications

References 33 publications

Three-dimensional metallo-dielectric selective thermal emitters with high-temperature stability for thermophotovoltaic applications

Three-dimensional metallo-dielectric selective thermal emitters with high-temperature stability for thermophotovoltaic applications

Introducing Defects in 3D Photonic Crystals: State of the Art

Controlled nonuniformity in macroporous silicon pore growth

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