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WO2001086038A2 - Materiaux a bande interdite photonique a base de germanium - Google Patents

Materiaux a bande interdite photonique a base de germanium Download PDF

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Publication number
WO2001086038A2
WO2001086038A2 PCT/CA2001/000621 CA0100621W WO0186038A2 WO 2001086038 A2 WO2001086038 A2 WO 2001086038A2 CA 0100621 W CA0100621 W CA 0100621W WO 0186038 A2 WO0186038 A2 WO 0186038A2
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Prior art keywords
germanium
opal
template
composite material
silica
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PCT/CA2001/000621
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WO2001086038A3 (fr
Inventor
Ceferino Lopez Fernandez
Francisco Javier Meseguer Rico
Hernan Miguez Garcia
Sajeev John
Geoffrey Alan Ozin
Emmanuel Benjamin Chomski
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Universidad Politecnica De Valencia
Consejo Superior De Investigaciones Cientificas
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Priority to AU2001258087A priority Critical patent/AU2001258087A1/en
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Publication of WO2001086038A3 publication Critical patent/WO2001086038A3/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y20/00—Nanooptics, e.g. quantum optics or photonic crystals
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
    • C30B29/60—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape characterised by shape
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B33/00—After-treatment of single crystals or homogeneous polycrystalline material with defined structure
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B5/00—Single-crystal growth from gels
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
    • G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
    • G02B6/122—Basic optical elements, e.g. light-guiding paths
    • G02B6/1225—Basic optical elements, e.g. light-guiding paths comprising photonic band-gap structures or photonic lattices

Definitions

  • the present invention relates to a method of synthesis of periodic composite materials of germanium and another material with a dielectric constant less than germanium, and more particularly the invention relates to photonic band gap (PBG) materials based on germanium having complete photonic bandgaps.
  • PBG photonic band gap
  • Photonics is the science of molding the flow of light.
  • Photonic band gap (PBG) materials as disclosed in S. John, Phys. Rev. Lett. 58, 2486 (1987), and E. Yablonovitch, Phys. Rev. Lett. 58, 2059 (1987), are a new class of dielectrics which carry the concept of molding the flow of light to its ultimate level, namely by facilitating the coherent localization of light, see S. John, Phys. Rev. Lett. 53,
  • PBG materials infiltrated with suitable liquid crystals, may exhibit fully tunable photonic band structures [see K. Busch and S. John, Phys. Rev. Lett. 83, 967 (1999) and E. Yablonovitch, Nature 401, 539 (1999)] enabling the steering of light flow by an external voltage.
  • PBG materials may play a role in photonics, analogous to the role of semiconductors in conventional microelectronics.
  • Sir John Maddox "If only it were possible to make dielectric materials in which electromagnetic waves cannot propagate at certain frequencies, all kinds of almost magical things would be possible.” John Maddox, Nature 348, 481 (1990).
  • a germanium inverse opal With such a germanium inverse opal, a large number of photonic devices can be integrated into a single three-dimensional optical chip.
  • PBG photonic band gap
  • Method (1) One of them consists of the infiltration of a germanium alkoxide within the void lattice of a silica opal template. The alkoxide is later hydrolyzed to form germanium oxide. Then, the germanium oxide is reduced to germanium in a hydrogen atmosphere at high temperature. This process is performed in a cyclic way until the desired amount of germanium is infiltrated.
  • Method (2) The other infiltration method is the chemical vapor deposition of germanium into a self-assembling silica opal template.
  • the materials presented here show the highest periodic dielectric contrast ever achieved in the near infrared (NIR) region. This achievement opens a new door for complete control of radiative emission from atoms and molecules, light localization and the integration of micron scale photonic devices into a three- dimensional all-optical micro-chip.
  • NIR near infrared
  • the present invention provides two different methods for the synthesis of a 0.1 mm to 1.0 cm scale single crystal of a face centered cubic
  • germanium PBG material comprising a close packed 1.0 -2.0 micron diameter air spheres in pure germanium. These germanium PBG materials show large reflection peaks in the NIR, resulting from the appearance of PBGs.
  • the self- assembly synthetic approach that we employ is straightforward, mild, inexpensive, accurate, and yields inverse opal structures made of germanium comprising up to 10,000 x 10,000 x 10,000 unit cells into which various defect network architectures can be imprinted during the initial stage of synthesis.
  • the methodology is compatible with, and can be easily integrated into, existing germanium fabrication manufacturing facilities.
  • a three dimensional periodic composite material comprising germanium and at least one other dielectric component having an effective dielectric constant smaller than the dielectric constant of germanium, the periodic composite material having a lattice periodicity ranging from about 1.0 microns to about 2.0 microns.
  • an inverse germanium opal comprising close packed spherical air voids in germanium, the spherical air voids having a diameter in a range from about 1.0 to about 2.0 microns.
  • a method of growing an inverse germanium opal comprising: providing a three dimensional opal template comprising particles having an effective geometry and composition; infiltrating the opal template with an effective amount of germanium into voids between said particles; and etching out the particles to produce an inverse germanium opal.
  • the present invention also provides a method of growing an inverse germanium opal, comprising: providing a three dimensional silica opal template made of silica spheres; infiltrating voids in the silica opal template with enough germanium to fill between about 50% to about 100% of said voids; and etching the silica spheres out of the template to produce an inverse germanium opal.
  • the present invention also provides a method of growing an inverse germanium opal with a complete three dimensional photonic bandgap, comprising: providing a three dimensional silica opal template including substantially mono-disperse silica spheres having a diameter in a range from about 1.0 to about 2.0 microns; infiltrating voids in the silica opal template with enough germanium to fill between about 50% to about 100% of said voids; and etching all the silica out of the template to produce an inverse germanium opal.
  • a method of growing an inverse germanium opal with a complete three dimensional photonic bandgap comprising: providing a three dimensional silica opal template including substantially mono-disperse silica spheres having a diameter in a range from about 1.0 to about 2.0 microns; infiltrating voids in the silica opal template with enough germanium to fill between about 50% to about 100% of said voids; and etching all the
  • Figure 1 shows a diagram of the cyclic process employed to infiltrate germanium in the void lattice of the silica opal template in accordance with the method number (1 ) of the present invention.
  • Figure 2 shows the PXRD pattern of the germanium infiltrated opal. The peaks observed correspond to the diamond like structure of bulk germanium.
  • Figure 3 is a scanning electron micrograph (SEM) of a (A) ⁇ 11 1 ⁇ and (B)
  • Figure 4 show SEM images of different types of internal fee facets: (A) ⁇ 100 ⁇ (B) ⁇ 1 10 ⁇ and (C) ⁇ 1 11 ⁇ of a germanium inverse opal produced in accordance with the method number (1 ) of the present invention.
  • Figure 5 is a typical MicroRaman spectrum of the inverse opal. The r 25 phonon of germanium can be clearly observed.
  • Figure 6 shows the reflectance spectrum of a germanium inverse opal with a 1.14 ⁇ m lattice parameter together with the corresponding photonic band.
  • the composition of the photonic crystal is 85% air and 15% germanium.
  • Figure 7 shows the calculated band structure of the germanium fee lattice made of 15% germanium and 85% air.
  • the shaded region shows the calculated positions of the complete photonic bandgap.
  • Figure 8 is a SEM image of a germanium infiltrated silica opal prepared using Method (2) having a lattice parameter of 1.7 microns.
  • Figure 9 is a low magnification SEM image of the germanium inverse opal (lattice parameter 1.7 microns) prepared using Method (2) showing the long range order in the resulting inverse opal.
  • Figure 10 shows an SEM image of a ⁇ 110 ⁇ face of the germanium fee structure prepared using Method (2) wherein the large holes connecting the air spherical cavities reflects the strong sintering between silica spheres in the template.
  • Figure 11 shows a reflectance spectra of the germanium inverse opal in which only the electronic transparency region ( ⁇ >1.85 microns) is shown.
  • Figure 12 shows a calculated complete photonic band structure for the germanium inverse opal shown in Figures 8-10 in which the full photonic band gap is highlighted.
  • a three dimensional periodic composite material comprising germanium and a dielectric component having a dielectric constant smaller than the dielectric constant of germanium.
  • the periodic composite material has a cubic lattice periodicity (center to center distance between adjacent cubic repeating units) ranging from about 1.0 microns to about 2.0 microns.
  • the dielectric constant of the lower dielectric component is in a range from about 1 to about 2.1 and said composite material is characterized by at least one complete photonic bandgap centered in the range of 1.9 to 4.0 microns.
  • a preferred method of producing this germanium/dielectric material composite involves producing an inverse germanium opal from a sintered silica opal with the silica opal produced using monodisperse silica spheres of selected diameter, which are ordered in an fee lattice and sintered at a temperature between 1223 K and 1323 K to give them mechanical stability and control the filling factor. Details of an exemplary, non-limiting method of fabrication of a silica opal are as follows.
  • the next step in the fabrication of an artificial opal is the crystallization of the silica spheres into a three dimensional periodic structure or template.
  • the inventors have discovered that different methods for settling silica spheres are needed depending on the sphere diameter.
  • Domain size ranges from 20 to >100 microns.
  • EXAMPLE 2 i) Crystallization Of 0.448 ⁇ 0.006 Micron Diameter Silica Spheres Initially 175 mg of such spheres were dispersed in 180 cm 3 of double distilled water. Spheres were let to settle during 7 days on the mentioned above substrate. The supernatant liquid was then removed until a 2 mm high liquid column was left above the sediment. The sedimentation tube was then placed in an oven at 60°C until the whole liquid evaporated (1 day). The sediment was then carefully removed from the substrate and its internal structure analyzed.
  • Natural sedimentation presents two problems. The first one is the time required to obtain an opal. If the silica spheres are too small (under 0.30 microns of diameter), several weeks are needed or even they may not settle at all because thermal agitation compensates gravitational forces. The other difficulty that has been observed is related to heavy spheres which are over 0.56 microns in diameter. In this case the sedimentation velocity is such that it is difficult to achieve an ordered array and it becomes completely impossible if the diameter is further increased. In this situation, the electrophoretic phenomena offers a method for overcoming these two problems. Using the electric field to drive the sedimentation velocity and keep it around 0.4 mm/hour would solve the difficulties mentioned before.
  • F g l/6 ⁇ p s gd 3
  • F A l/6 ⁇ w gd 3
  • F f 3 ⁇ vd
  • the electrophoretic mobility can be obtained in a straightforward manner if Stokes velocity is subtracted from the experimental velocity of the sample under a known electric field. Once the mobility is determined, the electric field necessary to achieve a given velocity can be stated beforehand.
  • the electrophoresis cell comprised a cylindrical tube (2 cm of diameter) of poly(methylacrylate) fixed to the base where the opal should settle, obtained from a standard silicon wafer sputtered with titanium or gold (with less than 0.1 nm of rugosity and thick enough to assure a good conductivity).
  • the material used for the upper electrodes were platinum because it has the highest redox potential so that electrolysis is avoided. Both electrodes are connected to a dc source in order to develop an electrical field. With this method sediments with thickness ranging between a few monolayers and 1 mm (depending on the amount of silica spheres used) with surface areas about 3.1 cm 2 are produced. To measure the sedimentation velocity, the height descended by the colloid/clear water interface (setting 0 mm the initial height) was monitored with time.
  • silica spheres with a diameter of 0.87 microns were settled both in the presence and absence of an electric field.
  • a suspension containing silica spheres of small diameter would take up to two months to settle to produce the sediment.
  • the settling rate using electrophoretic assisted sedimentation was accelerated from 0.09 mm/hour (natural velocity) to 0.35 mm/hour so that complete sedimentation was achieved in less than two weeks without decreasing the optical quality.
  • Diffraction studies of the as-grown opal showed Bragg peaks which denoted the presence of order within the opal.
  • Sintering provides an accurate way to control the filling fraction between 74% and 100%) of silica in opals.
  • the process of necking allows tuning of the dimensions of the silica opal and the resulting inverse silicon opal.
  • the process of necking also provides mechanical stability to the template in addition to providing a control over the opal void volume for subsequent synthesis and providing the connected network topology for removal of the template by an etching process.
  • silica opals sintered at 950°C for 3 hours have a mechanically stabilized compact face centered cubic (fee) structure with a silica filling factor of 74%. Further, sintering the opals at different temperatures between 950°C and 1100°C for different periods of time provided a method of controlling or tuning the optical properties and the free volume in the opals.
  • Example 5 provides an illustrative, non-limiting example of use of sintering temperature for tuning the optical and physical properties of a silica opal.
  • Pieces of an opal synthesized from 0.426 micron diameter spheres were sintered at 1025°C for different periods of time.
  • One piece of the opal was placed in an oven and heated up to 70°C employing a temperature gradient of 17min. Once the temperature reached 70°C it was kept constant at 70°C for 3 hours to prevent rapid or abrupt water de-sorption from the opal. After this, the temperature was increased up to 1025°C employing a temperature gradient of 1°/min. The opal was maintained at this temperature for 3 hours.
  • Two other pieces of the starting opal were sintered using the same procedure but one piece was sintered for 6 hours and the other for 12 hours. Characterization of the optical properties of the differently sintered opals reveal the free volume of the three opal pieces were different, decreasing with increasing temperature.
  • the present method provides two non-limiting methods of producing germanium based photonic crystals.
  • Figures 1 to 7 relate to method (1 ), with the example being fabrication of a photonic crystal having a germanium inverse opal structure with a 1.14 microns lattice parameter for the opal .
  • Figures 8 to 12 relates to method (2) for producing a photonic crystal based on a germanium inverse opal with a 1.7 micron lattice parameter of the opal.
  • a major advantage obtained by producing an inverse germanium opal in accordance with the present invention is that composites with complete photonic bandgaps can be economically synthesized which heretofore has not been realized.
  • Germanium (Ge) was grown inside the void spaces of the silica opal template using tetramethoxyorthogermanate (99% purity Ge(OCH 3 ) 4 , TMOG) liquid as a precursor, which easily infiltrates porous silica. TMOG infiltration takes place at room temperature. Once the silica opal template is fully infiltrated, TMOG is hydrolyzed to form germanium oxide (GeO 2 ) within the spaces between spheres. Once the GeO 2 is formed, it was reduced to Ge at a temperature of 823 K and in hydrogen (H 2 ) atmosphere. The GeO 2 may be reduced in a range of temperatures.
  • Example 1 provides illustrative, non- limiting examples of use of germanium infiltration into the silica opal template and etching of the silica template.
  • tetramethoxyorthogermanate is a preferred material for infiltration into the opal template
  • other liquid or aqueous/non- aqueous solution phase germanium-based reagents which can be hydrolyzed and/or calcined in air-or oxygen through to germanium dioxide and then reduced to germanium could also be used.
  • the sintered silica opal was placed in a hermetically sealed cell in which vacuum (10 ⁇ 2 torr) was made. In this way, the whole pore volume in the opal was available to subsequently infiltrated materials; hence, a complete and homogeneous infiltration was possible.
  • the template was then embedded in
  • TMOG was hydrolyzed at room temperature by flowing a mixture of N 2 and H z O vapor, which gave rise to GeO 2 formation in the opal lattice.
  • Ge° was formed from GeO 2 by direct reduction in H 2 atmosphere at 823 K.
  • the opal was subjected to five rounds of the GeO 2 and Ge formation processes just described.
  • Figure 1 shows a diagram of the cyclic process employed.
  • the Ge infiltrated opal was chemically etched in a 1 wt. % hydrofluoric acid in water solution.
  • the SiO 2 spheres of the matrix were removed to obtain Ge inverse opals.
  • Template sintering was responsible for the formation of necks between the SiO 2 spheres, a treatment which not only conferred robustness to the structure but also allowed the HF solution to flow through the whole structure as the SiO 2 was being removed.
  • X-ray diffraction of the germanium infiltrated opal (five infiltration cycles) indicated that the synthesized germanium was crystalline.
  • the XRD pattern is shown in Figure 2.
  • SEM characterization of the internal facets showed that a good connectivity of the germanium guest lattice is achieved after five cycles. This can be seen in Figure 3.
  • a thick layer of the opal template is present and a homogeneous and high degree of infiltration.
  • MRS Micro-Raman spectroscopy
  • the optical feature of a macro-porous germanium fee structure presenting a 1.14 ⁇ m lattice parameter was measured by focusing white light in a 20x20 ⁇ m spot on a single domain.
  • the experimental set-up determines that radiation propagates close to the r-L direction inside the crystal.
  • the reflectivity spectrum obtained is shown in figure 6.
  • Photonic band structure calculations based on the plane wave method are also shown. The best fit was achieved assuming a mesh of germanium occupying 15.6% of the whole volume. We only show the band structure along directions that are relevant for understanding the experiments (r-L and L-U). Three clear peaks can be observed in the spectrum. They correspond to different minima in the photonic local density of states (DOS) around the L point, as can be seen in the calculation.
  • DOS photonic local density of states
  • the peak at lower energy (0.60 eV) appears in the transparent region of bulk germanium. It corresponds to the first non-complete stop band, as can be seen in the band structure, since it vary with the propagation direction.
  • the indirect and direct electronic band gaps are placed at 0.67 eV and 0.79 eV respectively. So, the second peak in the reflectance, corresponding to the second stop frequency photonic band is above the indirect electronic gap and close to the direct one.
  • the small peak observable around 1 eV falls deep inside the Ge absorption region, above both electronic band gaps.
  • This peak presents a 12% gap width to midgap ratio and must correspond to the full PBG (predicted by S ⁇ z ⁇ er, H.S., Haus, J.W. & Inguva, R. Phys. Rev. B 45, 13962-13972 (1993); Busch, K. & John, S. Phys. Rev. E 58, 3896 (1998)). Its low intensity is due to the fact that the gap appears in the germanium electronic absorption region.
  • Germanium is grown inside the voids of the template by chemical vapor deposition (CVD) preferably using a mixture of 20% digermane (Ge 2 H 6 ) gas and 80%) hydrogen (H 2 ) gas as a precursor.
  • CVD chemical vapor deposition
  • the template is placed in a quartz vessel and evacuated using a vacuum pump to about 5*10 "6 torr.
  • the digermane/hydrogen gas mixture is added to the vessel.
  • the vessel is heated for varying times and temperatures to obtain samples with different degrees of infiltration.
  • the vessel is then evacuated using a vacuum pump to removed unreacted digermane and hydrogen.
  • the germanium is in the form of amorphous hydrogenated germanium. Heating of the sample drives off the hydrogen to form amorphous germanium. The sample can be heated further to form polycrystalline germanium. Typically the samples are annealed at 500°C in order to improve the germanium crystallinity and to allow diffusion of germanium inside the void structure.
  • germanium halides alkylgermaniumhydrides, alkylgermaniumhalides, alkylgermaniums, germaniumacetylacetonates all typically used in the presence of hydrogen.
  • Example 2 provides illustrative, non-limiting examples of use of germanium infiltration into the silica opal template and annealing of the germanium in the template using this method.
  • the germanium infiltrated sample was later etched by immersing it in a 1 % HF solution for 48 hours.
  • the sample was previously cut into pieces to favor the penetration of the solution into the silica/germanium composite opal.
  • a germanium inverse opal which has inherited the long- range order of the original template, as can be seen in Figure 9.
  • a careful inspection of the cleaved edges of the sample permits us to see different crystalline planes of the germanium face centered cubic structure.
  • a ⁇ 110 ⁇ face is shown in Figure 10.
  • the optical properties of the germanium inverse opal are measured in reflection mode.
  • the reflectance spectrum shows clear peaks that reveal the optical quality of the material and confirms its photonic band gap behavior.
  • Several measurements were taken focusing the incident beam in different areas of the sample surface. These confirm the homogeneous infiltration in the whole template and the uniformity of the germanium layer coating the spheres.
  • the method of producing the periodic silicon-air composites starting with silica opals and producing the inverse opals therefrom is a preferred or best mode known at present since the periodicity of the opal can be efficiently transferred to the inverse opal.
  • synthesis of periodic silicon-air composites or variants thereof as disclosed herein will not be restricted to conversion of silica opals.
  • Other silica templates and non-silica templates may be employed.
  • Silica templates involving lattice structures other than the close packed face center cubic lattice may be used and templates using two or more different sphere sizes may be used. These include for example the hexagonal close packed structure, the body center cubic structure, the diamond lattice structure, the hexagonal AB 2 structure.
  • Non-silica templates include periodically arrayed block co-polymers and other self- assembling organic materials. In this case non-spherical, repeating units can be realized. Here a multi-stage infiltration process is required since the polymeric material may not withstand the high temperatures required for silicon CVD.
  • a material such as silica would be infiltrated into the polymer template and the polymer template will be removed, prior to the final infiltration with silicon and the final removal of silica.
  • germanium photonic crystals grown by the present method may not have a complete PBG but only a photonic pseudo-gap, that is to say a material for which there is a large suppression in the total photon density of states (DOS) from what it would be in either air or in bulk silicon, have important applications as well. From theoretical studies (see S. John and T. Quang, Physical Review Letters 78, 1888 (1997)), it is known that even a sharp drop in the DOS by a factor of 2 over a small frequency range would lead to novel optical switching devices.
  • DOS total photon density of states
  • the local density of states controls the rate of spontaneous emission of light from atoms and molecules at particular locations in the photonic crystal, for lasing and optical switching applications.
  • the pseudogap material encompasses a broader range of materials and composites than the rather restricted set of materials which exhibit a complete PBG. Likewise, materials with a complete gap or pseudogap in the
  • LDOS encompass an even broader range of materials than those which exhibit corresponding gaps in the total density of states.
  • the LDOS is the density of states as felt by an atom or molecule in a particular position in the photonic crystal. As stated above, a gap in the LDOS may occur under less restrictive conditions than those required for a gap in the total DOS. For microlaser device applications, it is contemplated that low threshold laser action may be achieved with a gap only in the LDOS where the light emitting atoms are actually situated. The LDOS is what actually controls the radiative dynamics of individual atoms and molecules. Finally, it should be noted that whereas the total DOS may only have a gap of only 10% in a silicon inverse opal with a "complete 3-d PBG", the LDOS may exhibit a gap of up to 20% in the same material.
  • germanium-air composites comprising doped germanium are useful as sensors.
  • the germanium may be doped n-type by doping with phosphorus or p-type obtained by doping with boron.
  • the dopant is incorporated by infiltrating the germanium in the presence of gaseous phosphenes or boranes.
  • Such a three dimensional periodic composite material comprising germanium and a dielectric component having a dielectric constant small than a dielectric constant of germanium is treated by anodic oxidation to render it luminescent.
  • the doped macroporous germanium crystal with controlled porosity germanium walls functions as a chemoselective sensor to discriminate optically between molecules in a mixture, depending on the diameter of the pores that are grown in the germanium walls.

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Abstract

L'invention concerne des matériaux à bande interdite photonique à base de germanium ainsi que des procédés de synthèse de matériaux à bande interdite photonique (BIP) à base de germanium. Cette synthèse et caractérisation sont celles de matériaux à bande interdite photonique (BIP) cubique à faces centrées de pur germanium, de grande qualité, à très grande échelle, possédant des BIP tridimensionnelles dans la région proche infrarouge. Deux procédés différents permettent d'obtenir ce résultat. (1) Par infiltration d'un gabarit d'opale de silice auto-assemblant avec un alcoxyde de germanium qui est ensuite soumis à hydrolyse afin de former un oxyde de germanium(IV). Ce composé est ensuite réduit à un germanium(0) dans une atmosphère hydrogène. Ce cycle est répété jusqu'à ce que l'infiltration de germanium voulue soit atteinte. Une fois que le réseau hôte de germanium est formé, le gabarit est retiré et une opale inverse de germanium est obtenue. (2) Par déposition chimique en phase vapeur de germanium dans un gabarit d'opale de silice auto-assemblant, puis par retrait du gabarit. Par cette invention, un objectif de longue date est atteint dans le domaine des matériaux photoniques et de nouvelles possibilités se présentent, permettant la commande totale des émissions radiatives des atomes et des molécules, la localisation de la lumière et l'intégration de dispositifs photoniques à l'échelle des microns dans un mini circuit intégré entièrement optique tridimensionnel.
PCT/CA2001/000621 2000-05-05 2001-05-04 Materiaux a bande interdite photonique a base de germanium WO2001086038A2 (fr)

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AU2001258087A AU2001258087A1 (en) 2000-05-05 2001-05-04 Photonic bandgap materials based on germanium

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US60/202,115 2000-05-05

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WO2004031102A1 (fr) * 2002-09-30 2004-04-15 Merck Patent Gmbh Procede de production de structures opales inverses
WO2004029336A3 (fr) * 2002-09-27 2004-06-03 Univ Toronto Amelioration de la stabilite mecanique au moyen de la commande de la dimension des pores et de la connectivite dans des cristaux colloidaux par croissance couche par couche d'oxyde
EP1428911A1 (fr) * 2002-12-13 2004-06-16 Lucent Technologies Inc. Croissance cristalline assistée par un réseau de support
WO2004053205A3 (fr) * 2002-07-22 2004-11-11 Massachusetts Inst Of Technolg Formation de materiau poreux par depot chimique en phase vapeur sur des matrices de cristaux colloidaux
WO2004070089A3 (fr) * 2003-02-05 2005-01-20 Univ Cambridge Tech Depot de couches sur des substrats
DE102004052456A1 (de) * 2004-09-30 2006-04-13 Osram Opto Semiconductors Gmbh Strahlungsemittierendes Bauelement und Verfahren zu dessen Herstellung
US7106938B2 (en) 2004-03-16 2006-09-12 Regents Of The University Of Minnesota Self assembled three-dimensional photonic crystal
US7186460B2 (en) 2002-02-01 2007-03-06 Merck Patent Gmbh Extension and upsetting sensor
US7241502B2 (en) 2001-09-14 2007-07-10 Merck Patentgesellschaft Moulded bodies consisting of core-shell particles
US7291394B2 (en) 2002-06-17 2007-11-06 Merck Patent Gmbh Composite material containing a core-covering particle
US7767903B2 (en) 2003-11-10 2010-08-03 Marshall Robert A System and method for thermal to electric conversion

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US5385114A (en) * 1992-12-04 1995-01-31 Milstein; Joseph B. Photonic band gap materials and method of preparation thereof
US5600483A (en) * 1994-05-10 1997-02-04 Massachusetts Institute Of Technology Three-dimensional periodic dielectric structures having photonic bandgaps
GB9717407D0 (en) * 1997-08-18 1997-10-22 Isis Innovation Photonic crystal materials and a method of preparation thereof
US6134043A (en) * 1998-08-11 2000-10-17 Massachusetts Institute Of Technology Composite photonic crystals
US6261469B1 (en) * 1998-10-13 2001-07-17 Honeywell International Inc. Three dimensionally periodic structural assemblies on nanometer and longer scales
EP1279053A2 (fr) * 2000-01-28 2003-01-29 The Governing Council Of The University Of Toronto Mati res de bande interdite photonique base de silicium

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US7241502B2 (en) 2001-09-14 2007-07-10 Merck Patentgesellschaft Moulded bodies consisting of core-shell particles
US7186460B2 (en) 2002-02-01 2007-03-06 Merck Patent Gmbh Extension and upsetting sensor
US7291394B2 (en) 2002-06-17 2007-11-06 Merck Patent Gmbh Composite material containing a core-covering particle
WO2004053205A3 (fr) * 2002-07-22 2004-11-11 Massachusetts Inst Of Technolg Formation de materiau poreux par depot chimique en phase vapeur sur des matrices de cristaux colloidaux
US7112615B2 (en) 2002-07-22 2006-09-26 Massachusetts Institute Of Technology Porous material formation by chemical vapor deposition onto colloidal crystal templates
WO2004029336A3 (fr) * 2002-09-27 2004-06-03 Univ Toronto Amelioration de la stabilite mecanique au moyen de la commande de la dimension des pores et de la connectivite dans des cristaux colloidaux par croissance couche par couche d'oxyde
WO2004031102A1 (fr) * 2002-09-30 2004-04-15 Merck Patent Gmbh Procede de production de structures opales inverses
JP2004196645A (ja) * 2002-12-13 2004-07-15 Lucent Technol Inc フレームワークを援用した結晶成長
KR101050675B1 (ko) * 2002-12-13 2011-07-21 알카텔-루센트 유에스에이 인코포레이티드 프레임워크의 도움을 받는 결정 성장
US6960255B2 (en) 2002-12-13 2005-11-01 Lucent Technologies Inc. Framework assisted crystal growth
EP1428911A1 (fr) * 2002-12-13 2004-06-16 Lucent Technologies Inc. Croissance cristalline assistée par un réseau de support
GB2414018A (en) * 2003-02-05 2005-11-16 Univ Cambridge Tech Deposition of layers on substrates
GB2414018B (en) * 2003-02-05 2007-07-25 Univ Cambridge Tech Deposition of material in substrates
US7678409B2 (en) 2003-02-05 2010-03-16 Cambridge Enterprise Limited Deposition of layers on substrates
WO2004070089A3 (fr) * 2003-02-05 2005-01-20 Univ Cambridge Tech Depot de couches sur des substrats
US7767903B2 (en) 2003-11-10 2010-08-03 Marshall Robert A System and method for thermal to electric conversion
US7106938B2 (en) 2004-03-16 2006-09-12 Regents Of The University Of Minnesota Self assembled three-dimensional photonic crystal
DE102004052456A1 (de) * 2004-09-30 2006-04-13 Osram Opto Semiconductors Gmbh Strahlungsemittierendes Bauelement und Verfahren zu dessen Herstellung
DE102004052456B4 (de) * 2004-09-30 2007-12-20 Osram Opto Semiconductors Gmbh Strahlungsemittierendes Bauelement und Verfahren zu dessen Herstellung

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