Photonic bandgap materials based on silicon

Abstract

Method of synthesis of photonic band gap (PBG) materials. The synthesis and characterization of high quality, very large scale, face centered cubic photonic band gap (PBG) materials consisting of pure silicon, exhibiting a complete three-dimensional PBG centered on a wavelength of 1.5 μm. This is obtained by chemical vapor deposition and anchoring of disilane into a self-assembling silica opal template, wetting of a thick silicon layer on the interior surfaces of the template, and subsequent removal of the template. This achievement realizes a long standing goal in photonic materials and 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.

Therefore what is claimed is:  
     
         1 . A three dimensional periodic composite material comprising silicon and at least one other dielectric component having an effective dielectric constant smaller than a dielectric constant of silicon, the periodic composite material having a lattice periodicity ranging from about 0.28 microns to about 1.8 microns.  
     
     
         2 . The periodic composite material according to  claim 1  having a face centered cubic lattice periodicity.  
     
     
         3 . The periodic composite material according to  claim 1  wherein said composite material is characterized by at least one pseudo-photonic band gap in the local photon density of states.  
     
     
         4 . The periodic composite material according to claims  1  or  2  wherein said composite material is characterized by at least one pseudo-photonic band gap in the total photon density of states.  
     
     
         5 . The periodic composite material according to claims  1  or  2  wherein said composite material has at least one complete photonic band gap in the local photon density of states.  
     
     
         6 . The periodic composite material according to claims  1  or  2  wherein said dielectric constant is in a range from about 1.0 to 1.6 and said complete photonic band gap is located in the total photon density of states.  
     
     
         7 . The periodic composite material according to claims  1  or  2  wherein said composite material is characterized by at least one complete photonic band gap in the total photon density of states spanning at least 5% of a center frequency of the photonic band gap.  
     
     
         8 . The periodic composite material according to  claim 3  wherein a ratio of said complete photonic band gap to a center frequency in the local density of states ranges from 0% to about 20%.  
     
     
         9 . The periodic composite material according to claims  1 ,  2 ,  3 ,  4 ,  5 ,  6 ,  7  or  8  wherein said dielectric component includes a silica-air or a germanium-air composite material.  
     
     
         10 . The periodic composite material according to  claim 4  wherein said low dielectric component is vacuum.  
     
     
         11 . The periodic composite material according to  claim 6  wherein said low dielectric component is air.  
     
     
         12 . The periodic composite material according to claims  1 ,  2 ,  3 ,  4 ,  5 ,  8 ,  9 ,  10  or  11  wherein said periodic composite material is an inverse silicon opal.  
     
     
         13 . The periodic composite material according to  claim 12  wherein said complete photonic bandgap is centered on a wavelength of about 1.5 microns.  
     
     
         14 . The periodic composite material according to claims  6 ,  7  or  11  wherein said complete photonic bandgap is adjustable by adjusting silicon to air ratio in said composite material.  
     
     
         15 . The periodic composite material according to  claims 1  to  14  wherein said silicon is selected from the group consisting of single crystal silicon, amorphous silicon, polycrystalline silicon, porous silicon and nanocrystalline silicon.  
     
     
         16 . The periodic composite material according to  claims 1  to  14  having dimensions in a range from 2×2×2 unit cells to a×b×c unit cells, wherein 2<a<10,000, 2<b<10,000, 2<c<10,000.  
     
     
         17 . The periodic composite material according to  claims 1  to  14  having a planar thin film geometry with dimensions in a range from 1×10×10 unit cells to a×b×c unit cells, wherein 1<a<100, 10<b, c<100,000.  
     
     
         18 . The periodic composite material according to  claims 1  to  17  wherein said silicon includes a silicon alloy.  
     
     
         19 . The periodic composite material according to  claims 1  to  17  wherein said silicon contains dopants, said dopants including magnetically sensitive dopants, electrically sensitive dopants and optically sensitive dopants.  
     
     
         20 . The periodic composite material according to  claim 19  wherein said doped silicon is selected from the group consisting of n-type silicon wherein said electrically sensitive dopant is phosphorous and p-type silicon wherein said electrically sensitive dopant is boron.  
     
     
         21 . The periodic composite material according to  claim 18  wherein said silicon alloy is selected from the group consisting of silicon-germanium alloys Si x Ge 1-x , 0<×<1, silicon-carbide alloys Si x C 1-x , 0<×<1, silicon-tungsten alloys, silicon-nickel alloys, silicon-titanium alloys, silicon-chromium alloys, silicon-aluminum alloys and silicon-molybdenum alloys.  
     
     
         22 . The periodic composite material according to  claim 19  wherein said optically sensitive dopants luminescence in a wavelength range substantially located in or near said photonic bandgap.  
     
     
         23 . The periodic composite material according to  claim 22  wherein said dopants emit light in a wavelength range from about 1.3 microns to about 1.7 microns.  
     
     
         24 . The periodic composite material according to  claim 23  wherein said dopants are selected from the group consisting of rare earth atoms, organic dyes, inorganic dyes, organic polymers and inorganic polymers.  
     
     
         25 . The periodic composite material according to  claim 24  wherein said dopant is erbium.  
     
     
         26 . The periodic composite material according to  claims 1  to  25  wherein said silicon includes optically sensitive molecules adsorbed or chemically bonded to a surface thereof.  
     
     
         27 . The periodic composite material according to  claim 26  wherein said optically sensitive molecules includes one of luminescent dyes and luminescent polymers.  
     
     
         28 . The periodic composite material according to  claims 1  to  25  wherein said silicon includes hydrophilic or hydrophobic molecules adsorbed or chemically bonded to a surface thereof.  
     
     
         29 . The periodic composite material according to  claim 1  having a hexagonal close-packed or body centered cubic lattice periodicity.  
     
     
         30 . An inverse silicon opal comprising close packed spherical air voids in silicon, the spherical air voids having a diameter in a range from about 0.2 to about 1.3 microns.  
     
     
         31 . The inverse silicon opal according to  claim 30  wherein said air voids have a diameter between about 0.8 to about 0.9 microns.  
     
     
         32 . The inverse silicon opal according to  claim 31  characterized by a complete photonic bandgap centered on a wavelength in a range from about 1.3 to about 1.7 microns.  
     
     
         33 . The inverse silicon opal according to claims  30 ,  31 ,  32  or  91  wherein said silicon is selected from the group consisting of single crystal silicon, polycrystalline silicon, nanocrystalline silicon, porous silicon and amorphous silicon.  
     
     
         34 . The inverse silicon opal according to claims  30 ,  31 ,  32 ,  33  or  91  having dimensions in a range from 2×2×2 unit cells to a×b×c unit cells, wherein 2<a<10,000, 2<b<10,000, 2<c<10,000.  
     
     
         35 . The inverse silicon opal according to claims  30 ,  31 ,  32 ,  33 , or  91  having a planar thin film geometry with dimensions in a range from 1×10×10 unit cells to a×b×c unit cells, wherein 1<a<100, 10<b, c<100,000.  
     
     
         36 . A method of growing an inverse silicon 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 silicon into voids between said particles; and    etching out the particles to produce an inverse silicon opal.    
     
     
         37 . The method according to  claim 36  wherein said particles are substantially spherical particles in a face centered cubic lattice and the amount of silicon infiltrated is enough to fill between about 80% to about 100% of said voids.  
     
     
         38 . The method according to  claim 37  wherein said spherical particles are silica spheres.  
     
     
         39 . The method according to  claim 38  wherein said silica spheres are mono-disperse and have a diameter in a range from about 0.2 to about 1.3 microns.  
     
     
         40 . The method according to claims  36 ,  37 ,  38  or  39  wherein said opal template is infiltrated with enough silicon to fill about 90% of said voids.  
     
     
         41 . The method according to claims  36 ,  37 ,  38 ,  39  or  40  wherein after infiltrating the opal template with silicon the infiltrated template is annealed to assist diffusion of silicon into said voids in the template.  
     
     
         42 . The method according to claims  36 ,  37 ,  38 ,  39 ,  40  or  41  wherein the three dimensional template has dimensions in a range from 2×2×2 unit cells to a×b×c unit cells, wherein 2<a<10,000, 2<b<10,000, 2<c<10,000.  
     
     
         43 . The inverse silicon opal according to claims  36 ,  37 ,  38 ,  39 ,  40  or  41  having a planar thin film geometry with dimensions in a range from 1×10×10 unit cells to a×b×c unit cells, wherein 1<a<100, 10<b, c<100,000.  
     
     
         44 . A method of growing an inverse silicon opal, comprising: 
 providing a three dimensional silica opal template made of silica spheres;    infiltrating voids in the silica opal template with enough silicon to fill between about 80% to about 100% of said voids; and    etching the silica spheres out of the template to produce an inverse silicon opal.    
     
     
         45 . The method according to  claim 44  wherein the silica spheres are substantially monodisperse having a diameter in a range from about 0.2 to about 1.3 microns.  
     
     
         46 . The method according to  claim 45  wherein said diameter is between about 0.8 to about 0.9 microns and said silica template is infiltrated with enough silicon to fill about 90% of said voids.  
     
     
         47 . The method according to claims  44 ,  45  or  46  wherein the silica opal template is infiltrated by chemical vapor deposition using a gaseous silane-based precursor Si n H 2n+2  wherein n=1, 2, 3, . . .  
     
     
         48 . The method according to claims  44 ,  45 ,  46  or  47  wherein the silica opal template is infiltrated by chemical vapor deposition using disilane (Si 2 H 6 ) gas as a precursor.  
     
     
         49 . The method according to claims  44 ,  45 ,  46 ,  47  or  48  wherein during infiltration of silicon into the silica opal template a temperature of the template is maintained in a range from about 100° C. to about 500° C.  
     
     
         50 . The method according to  claim 49  wherein the range is from about 250° C. to about 350° C.  
     
     
         51 . The method according to claims  44 ,  45 ,  46 ,  47 ,  48 ,  49  or  50  wherein after infiltrating the silica opal template with silicon the infiltrated template is annealed to assist diffusion of silicon into the voids in the template.  
     
     
         52 . The method according to claims  43 ,  44 ,  45 ,  46 ,  47 ,  48 ,  49 ,  50  or  51  wherein the three dimensional template has dimensions in a range from 2×2×2 unit cells to a×b×c unit cells, wherein 2<a<10,000, 2<b<10,000, 2<c<10,000.  
     
     
         53 . The method according to claims  44 ,  45 ,  46 ,  47 ,  48 ,  49 ,  50  or  51  having a planar thin film geometry with dimensions in a range from 1×10×10 unit cells to a×b×c unit cells, wherein 1<a<100, 10<b, c<100,000.  
     
     
         54 . The method according to claims  44 ,  45 ,  46 ,  47 ,  48 ,  49 ,  50 ,  51 ,  52  or  53  wherein the silica is chemically etched using a fluoride-based etching medium.  
     
     
         55 . The method according to  claim 44  wherein the silicon is impregnated into the silica opal template by one of laser ablation of Si atoms, molecular beam deposition of Si atoms or infiltration of colloidal silicon, silicon nanoclusters or silane-based polymers using one of either vapor impregnation, solution impregnation and melt impregnation.  
     
     
         56 . A method of growing an inverse silicon 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 0.55 to about 1.3 microns;    infiltrating voids in the silica opal template with enough silicon to fill between about 80% to about 100% of said voids; and    etching all the silica out of the template to produce an inverse silicon opal.    
     
     
         57 . The method according to  claim 56  wherein said diameter is between about 0.8 to about 0.9 microns.  
     
     
         58 . The method according to claims  56  or  57  wherein said opal template is infiltrated with enough silicon to fill about 90% of said voids.  
     
     
         59 . The method according to claims  56 ,  57  or  58  wherein the silica opal template is infiltrated by chemical vapor deposition using disilane (Si 2 H 6 ) gas as a precursor.  
     
     
         60 . The method according to claims  56 ,  57 ,  58  or  59  wherein the silicon is selected from the group consisting of single crystal silicon, polycrystalline silicon, nanocrystalline silicon, porous silicon and amorphous silicon.  
     
     
         61 . The method according to claims  56 ,  57 ,  58 ,  59  or  60  wherein after infiltrating the silica opal template with silicon the infiltrated template is annealed to assist diffusion of silicon into the voids in the template to provide substantially uniform spatial distribution of silicon in said voids.  
     
     
         62 . The method according to claims  56 ,  57 ,  58 ,  59 ,  60  or  61  wherein the three dimensional template has dimensions in a range from 2×2×2 unit cells to a×b×c unit cells, wherein 2<a<10,000, 2<b<10,000, 2<c<10,000.  
     
     
         63 . The method according to claims  55 ,  56 ,  57 ,  58 ,  59 ,  60  or  61  having a planar thin film geometry with dimensions in a range from 1×10×10 unit cells to a×b×c unit cells, wherein 1<a<100, 10<b, c<100,000.  
     
     
         64 . A method of growing silica spheres having a diameter between about 0.55 microns to about 1.3 microns, comprising: 
 growing silica seed particles by rapidly adding a first amount of tetraethylorthosilicate (TEOS) to a stirred alcohol solution comprising water and aqueous ammonia to form a suspension of silica seed particles;    after a first effective period of time of stirring, enlarging the silica seed particles to silica spheres with a preselected diameter by slowly adding a second amount of tetraethylorthosilicate (TEOS) with stirring and thereafter stirring the suspension for a second effective period of time; and    collecting the silica spheres with a diameter between about 0.6 microns to about 1.3 microns from said suspension.    
     
     
         65 . The method according to  claim 64  wherein said aqueous solution includes between about 70% to about 90% (by volume) of absolute ethanol, between about 5% to about 15% (by volume) of aqueous ammonia (32% wt) and between about 2% to about 10% (by volume) of distilled water.  
     
     
         66 . The method according to  claim 65  wherein said aqueous solution includes about 79.6% (by volume) of absolute ethanol, about 10.8% (by volume) of aqueous ammonia (32% wt) and about 4.2% (by volume) of distilled water.  
     
     
         67 . The method according to  claim 64 ,  65  or  66  wherein said first amount of tetraethylorthosilicate is between about 4% to about 7% (by volume), and wherein said silica seed particles have a diameter in a range from about 0.5 microns to about 0.55 microns.  
     
     
         68 . The method according to  claim 65  wherein said second amount of tetraethylorthosilicate is between about 4% to about 12% (by volume), and wherein said silica spheres are substantially monodisperse having a diameter in a range between about 0.70 to about 0.90 microns.  
     
     
         69 . The method according to claims  92  or  93  including enlarging said silica spheres prior to collecting said silica spheres by adding a fourth amount of tetraethylorthosilicate (TEOS) with stirring and thereafter stirring the suspension for a fourth effective period of time.  
     
     
         70 . The method according to  claim 69  wherein said fourth amount of tetraethylorthosilicate is about 5% to about 20% (by volume), and wherein said silica spheres are substantially monodisperse having a diameter in a range between about 1.100 microns to about 1.500 microns.  
     
     
         71 . The method according to  claim 69  or  70  wherein said fourth amount of tetraethylorthosilicate is about 15% (by volume), and wherein said silica spheres are substantially monodisperse having a diameter in a range between about 1.300 microns to about 1.400 microns.  
     
     
         72 . A method of synthesizing an opal from silica spheres, comprising; 
 providing a suspension of silica spheres in a liquid, the silica spheres having an effective diameter and the liquid having an effective viscosity and density so said silica spheres settle with an effective velocity;    settling the silica spheres from said suspension at a first effective temperature to form a sediment of preselected dimensions; and    drying the sediment at a second effective temperature.    
     
     
         73 . The method according to  claim 72  wherein the silica spheres are substantially monodisperse having a diameter in a range from about 0.60 microns to about 1.3 microns.  
     
     
         74 . The method according to claims  72  or  73  wherein the effective liquid is selected from the group consisting of acetone, mixtures of acetone and water, polyalcohols and mixtures of polyalcohols and water.  
     
     
         75 . The method according to  claim 74  wherein said polyalcohols include glycerol, mixtures of glycerol and water, ethlyeneglycol and mixtures of ethlyeneglycol and water.  
     
     
         76 . The method according to claims  72 ,  73 ,  74  or  75  wherein the first effective temperature is in a range from about 0° C. to about 80° C.  
     
     
         77 . The method according to claims  72 ,  73 ,  74 ,  75  or  76  wherein the second effective temperature at which the sediment is dried is in a range from about 20° C. to about 100° C.  
     
     
         78 . The method according to claims  72 ,  73 ,  74 ,  75 ,  76  or  77  wherein an electric field is applied across the liquid for electrophoretic deposition of the silica spheres.  
     
     
         79 . The method according to  claim 78  wherein the electric field applied across the dispersion is in a range from about −200 V/m to about 200 V/m.  
     
     
         80 . The method according to claims  72 ,  73 ,  74 ,  75 ,  76 ,  77 ,  78  or  79  wherein the silica opal is grown with a morphology selected from the group consisting of microscopic to macroscopic dimension fibers, films, spheres, lithographic patterns and monoliths.  
     
     
         81 . The method according to  claim 80  wherein said microscopic to macroscopic cubic opals have dimensions in a range from 2×2×2 unit cells to a×b×c unit cells, wherein 2<a<10,000, 2<b<10,000, 2<c<10,000.  
     
     
         82 . The method according to  claim 80  having a planar thin film geometry with dimensions in a range from 1×10×10 unit cells to a×b×c unit cells, wherein 1<a<100, 10<b, c<100,000.  
     
     
         83 . The method according to claims  72 ,  73 ,  74 ,  75 ,  76 ,  77 ,  78 ,  79 ,  80 ,  81  or  82  including thermal treatment of the dried sediment.  
     
     
         84 . The method according to  claim 83  wherein said thermal treatment includes sintering the sediment at an effective temperature after it is dried to control packing of the silica spheres and void pore volume of the total opal volume.  
     
     
         85 . The method according to  claim 84  wherein said thermal treatment includes sintering the sediment at a temperature between about 950° C. and about 1100° C. for an effective period of time to adjust the void pore volume to a preselected volume.  
     
     
         86 . The method according to  claim 85  wherein said effective period of time is between 1 to 12 hours.  
     
     
         87 . The method according to  claim 85  wherein the sintering temperature is about 950° C. and the effective period of time is about 3 hours.  
     
     
         88 . The method according to claims  72 ,  73 ,  74 ,  75 ,  76 ,  77 ,  78 ,  79 ,  80 ,  81 ,  82 ,  83 ,  84 ,  85 ,  86  or  87  wherein the silica spheres are grown by; 
 growing silica seed particles by rapidly adding a first amount of tetraethylorthosilicate (TEOS) to a stirred aqueous solution comprising an alcohol and aqueous ammonia to form a suspension of silica seed particles; and  
 after a first effective period of time of stirring enlarging the silica seed particles to silica spheres with a preselected diameter by slowly adding a second amount of tetraethylorthosilicate (TEOS) with stirring and thereafter stirring the suspension for a second effective period of time.  
 collecting the silica spheres from said suspension.  
 
     
     
         89 . The method according to  claim 88  wherein said silica seed particles have a diameter in a range from about 0.5 microns to about 0.55 microns.  
     
     
         90 . The method according to claims  88  or  89  wherein said collected silica spheres are substantially mono-disperse silica spheres having a mean diameter of about 0.85 microns with a dispersity of about 3 to 5%.  
     
     
         91 . The inverse silicon opal according to claims  31  or  32  characterized by a complete photonic bandgap with a width to center frequency ratio in a range of 0 to about 9%.  
     
     
         92 . The method according to  claim 67  or  68  including enlarging said silica spheres prior to collecting said silica spheres by adding a third amount of tetraethylorthosilicate (TEOS) with stirring and thereafter stirring the suspension for a third effective period of time.  
     
     
         93 . The method according to  claim 92  wherein said third amount of tetraethylorthosilicate is about 5% to about 16% (by volume), and wherein said silica spheres are substantially monodisperse having a diameter in a range between about 1.070 microns to about 1.110 microns.