IR Edge Research Articles

TCT investigation of the one-sided depletion of low-temperature covalently bonded silicon sensor P-N diodes

In the context of particle detectors, low-temperature covalent wafer-wafer bonding allows for integration of high-Z materials as absorbing layers with readout chips produced in standard CMOS processes. This enables for instance the fabrication of novel highly efficient X-ray imaging sensors. In order to investigate the effects of the covalent bonding on the signal generated in such sensors, wafer-wafer bonded silicon-silicon P-N pad diodes have previously been produced. The behaviour of these test samples is being investigated with transient current technique (TCT) measurements. In this paper we present an overview of the TCT setup as well as a custom sandwich-type sample holder used for these measurements. A review of the results presented in a previous paper shows, that the bonded P-N structures show a highly asymmetric depletion behaviour under reverse bias. IR edge TCT measurements confirm that only the P-side of the samples is being depleted.

Spectroscopic Properties of TeO<sub>2</sub>-Bi<sub>2</sub>O<sub>3</sub>-ZnO-PbO Based Tellurite Glasses

Tellurite glasses with molar compositions of 55TeO2–2Bi2O3–[43-x] ZnO–xPbO (in mol%) with x= 1, 2, 3, 4, 5 was fabricated by melt quenching method. Their absorption spectra ranging from ultraviolet to infrared region were measured using UV-VIS-NIR spectrophotometer and FTIR. Minimum losses of all glasses were then estimated from the intersection of the ‘V’ curve formed from the intersection of the extrapolation of the IR edge on the long wavelength side of the spectrum and the scattering loss curve on the short wavelength side of the spectrum. From this work, it was that the estimated minimum loss of the investigated glasses were within the range between 2.31·10-3dB/m and 2.94·10-3 dB/m at wavelength around 5.5 μm.

Optical, Thermal, and Mechanical Characterization of Ga2 Se3 -Added GLS Glass.

Gallium lanthanum sulfide glass (GLS) has been widely studied in the last 40 years for middle-infrared applications. In this work, the results of the substitution of selenium for sulphur in GLS glass are described. The samples are prepared via melt-quench method in an argon-purged atmosphere. A wide range of compositional substitutions are studied to define the glass-forming region of the modified material. The complete substitution of Ga2 S3 by Ga2 Se3 is achieved by involving new higher quenching rate techniques compared to those containing only sulfides. The samples exhibiting glassy characteristics are further characterized. In particular, the optical and thermal properties of the sample are investigated in order to understand the role of selenium in the formation of the glass. The addition of selenium to GLS glass generally results in a lower glass transition temperature and an extended transmission window. Particularly, the IR edge is found to be extended from about 9 µm for GLS glass to about 15 µm for Se-added GLS glass defined by the 50% transmission point. Furthermore, the addition of selenium does not affect the UV edge dramatically. The role of selenium is hypothesized in the glass formation to explain these changes.

Development of novel ternary tellurite glasses for high temperature fiber optic mid-IR chemical sensing

The properties of novel ternary tellurite glasses, based on the TeO2–BaO–Bi2O3 system, are reported for their applications in on-line chemical sensing and process control by characterizing the fundamental frequencies of molecular vibrations in the 2–5μm spectral region of mid-IR. The chemical sensing for process control also requires above room temperature operation (>100°C) for prolonged periods of time. Bulk samples of ternary tellurite glasses with a number of different compositions were prepared using heavy molecular weight oxides of TeO2, BaO, and Bi2O3. Infrared and Raman spectroscopic analysis was carried out together with differential thermal analysis to study the relationship between glass structure and thermal and viscosity properties. The temperature dependence of the viscosities of the glasses is also reported. The compositional dependence of Raman frequency shifts and the corresponding change in the coordination of Te–O structure is discussed. The results from the IR edge, reflection spectroscopic, and wavelength dependence of refractive index are also reported.

Modeling Misfit Dislocation Arrays for the Growth of Low-Defect Density AlSb on Si

ABSTRACTWe present analytical models and experimental results to describe low-defect density growth (∼ 6 × 105/cm2) of highly mismatched antimonides on Si and GaAs substrates, with strain relief achieved at the growth interface through periodic, 90° interfacial misfit dislocations (IMF). We use molecular mechanics (MM) based modeling techniques to understand, at the atomic level, the spontaneous formation and energetics of these IMF. We have modeled, grown and characterized two systems extensively, these are - AlSb on Si with ∼ 13% mismatch and GaSb on GaAs with 7.83% lattice mismatch. Growth of these materials by molecular beam epitaxy (MBE) and subsequent High-Resolution Transmission Electron Microscopy (HR-TEM) has indicated that there is no tetragonal distortion in these two systems despite the high lattice mismatch. Instead, the mismatched epi-layers spontaneously form periodic IMF arrays that run along both [110] and [1-10] directions and relieve almost 100% of the strain in a few monolayers of deposition. To model this form of strain relief, we use existing theories of strain relief adapted for very high strain conditions and we also use bond energetics to model the strain-relieving interface. The IMFs in these systems are periodic and so is the deviation in bond lengths and bond angles, which restricts our calculation space to a finite number of elements. We shall also demonstrate extensive growth and characterization results of the materials grown with a particular emphasis on the strain-relieving interface to show excellent agreement of the experimental data with the proposed models. The high quality and low-defect density in AlSb grown on Si, has helped us demonstrate optically pumped IR VCSELs and edge emitters monolithically on Si (001) and this data will also be presented.

Reaction of ruthenium carbonyl chloride with iridium tetracarbonyl anion. Synthesis, crystal structure and characterisation of [Ru 2Ir 2H(CO) 12Cl]: a heterometallic tetranuclear butterfly cluster with chloride bridge

Reaction between [Ru 2(CO) 6Cl 4] and Na[Ir(CO) 4] in tetrahydrofuran (THF) yielded [Ru 2Ir 2H(CO) 12Cl], a new iridium–ruthenium mixed-metal cluster of possible catalytic interest. The cluster was characterised by 1H-NMR and infrared spectroscopy and by single-crystal X-ray structure analysis. [Ru 2Ir 2H(CO) 12Cl] exhibits a butterfly arrangement of metal atoms, with three terminal carbonyls on each metal atom, chloride ligand in the bridging position, and hydride ligand at the Ir–Ir edge. The trinuclear ruthenium cluster [Ru 3( μ-Cl) 2(CO) 8(PPhMe 2) 2] was synthesised by reaction of [Ru 2(CO) 6Cl 4] with K[Ir(CO) 4] in THF, followed by ligand substitution with [PPhMe 2] in CH 2Cl 2 at ambient temperature. Determination of the structure by X-ray diffraction showed it to consist of an open trinuclear unit involving two metal–metal bonds. The open edge of the metal framework is supported by two symmetric bridging chloride ligands. Both phosphorus ligands are cis to the chlorine atoms and trans to the unique ruthenium atom.

Complexes with Platinum−Iridium Bonds: Stepwise Formation of a PtIr2Cluster Complex

The reaction of [Pt(dppm)2]Cl2 (dppm = Ph2PCH2PPh2) with [Ir(CO)4]- and dppm in a 1:2:1 ratio leads in a multistep reaction to the new heteronuclear cluster complex [PtIr2(CO)2(μ-CO)(μ-dppm)3], which contains a triangle of metal atoms with each edge bridged by a dppm ligand and in which only the platinum atom is coordinatively unsaturated. The initial step in the reaction leads to formation of the neutral and cationic binuclear complexes [PtIrCl(CO)2(μ-dppm)2] and [PtIr(CO)3(μ-dppm)2]+, respectively. The binuclear complexes then react with additional [Ir(CO)4]- to form the cluster [PtIr2(CO)4(μ-CO)(μ-dppm)2] by insertion into a Pt−P linkage; this cluster can exist in two isomeric forms, each containing a triangular PtIr2 group with the Ir−Ir and one Pt−Ir edge bridged by dppm ligands but differing in stereochemistry. These isomers equilibrate slowly at room temperature, and each reacts easily with dppm to form the final cluster complex [PtIr2(CO)2(μ-CO)(μ-dppm)3]. The structures of the complexes [PtIr2(CO...

Rare-earth-doped cadmium-based chlorofluoride glasses with improved durability

Glass formation is investigated in mixed-halide systems based on CdF 2, NaF, BaF 2, ZnF 2, and CdCl 2. The compositions are optimized for the best compromise between glass stability and low sensitivity to hydrolysis. Addition of 1 mol % rare-earth fluoride does not affect significantly the glass stability. The multiphonon edge is found to depend directly on the chlorine content. Located beyond 9 μm, the position of the IR edge is indicative of low phonon-energy, as compared to pure fluorides. Fundamental vibrations of the host are obtained by means of Raman and far-IR transmission spectroscopies.

Complexes of Ir3(CO)3(η5-C9H7)3with Metal Fragment Electrophiles

The reactions of C3v Ir3(μ-CO)3(η5-C9H7)3 (1) with various metal electrophiles yield the cationic tetranuclear clusters [Ir3{M(PPh3)}(CO)3(η5-C9H7)3][PF6] (2, M = Cu; 3, M = Ag; 5, M = Au), [Ir3Tl(μ-CO)3(η5-C9H7)3][PF6] (4), and [Ir3(HgR)(CO)3(η5-C9H7)3][PF6] (6, R = Ph; 7, R = W(CO)3(η5-C5H5)). Compounds 5−7 are best prepared via compound 4. The structures of compounds 4 and 5 have been determined by X-ray diffraction. The C3v symmetry of the parent cluster 1 is maintained in the structure of 4. The molecule consists of a triangle of iridium atoms, each edge of which has a bridging carbonyl oriented out of the plane in the same direction and each vertex of which has an η5-indenyl ligand oriented toward the opposite side of the plane. The thallium atom adopts a face-capping mode of coordination on the same side of the triiridium plane as the three indenyl ligands and is encapsulated by the phenylene portions of the indenyl groups. The molecular structure of 5 consists of a AuIr3 butterfly framework with a hinge angle of 153.63(3)° and the gold atom in a wingtip position. Each CO ligand is bonded in a terminal mode to one iridium center, with one CO ligand ‘down' relative to the Ir3 plane and two CO ligands ‘up', flanking the Ir−Ir edge bridged by the Au(PPh3)+ fragment. The indenyl ligands take up positions opposite those of the CO ligands at each iridium center. The infrared and 1H NMR spectra of compounds 2, 3, 5, 6, and 7 are all very similar and are fully consistent with the solid-state structure of 5.

Properties of As40S(60–x) Sex Glasses for IR Fiber Optics

The physical and optical properties of glasses in the As40S((60‐x:)Sex system where x= 0, 5,10,15, and 20 at. % Se have been investigated. The changes in the glass transition temperature, density, hardness, IR edge, and refractive index can be attributed to the presence of Se, which simply replaces S in these glasses. The glasses do not exhibit crystallization under the conditions used in this study, which is a desirable property from the viewpoint of flberization. Appropriate core and cladding glass compositions have been identified for fabrication of optical fibers with known numerical apertures. Furthermore, it has been shown that these glasses will not impart additional thermal or mechanical stresses in optical fibers made from these compositions.

Heterometallic boride clusters: formation of octahedral [M2Ru4(CO)16B]–(M = Rh or Ir) and gold(I) phosphine derivatives. Crystal structures of [N(PPh3)2][trans-Ir2Ru4(CO)16B], trans-[Rh2Ru4(CO)16B{µ3-AuP(C6H11)3}] and cis-[Ir2Ru4(CO)16B{µ-AuP(C6H11)3}

The reaction of the butterfly cluster [Ru4H(CO)12BH]– with [Rh2(CO)4Cl2] led to the octahedral boride [Rh2Ru4(CO)16B]–1. In solution, 11B NMR spectroscopic evidence supports the presence of both cis- and trans-isomers of 1. The trans form is predominant. When treated with [AuCl{P(C6H11)3}], 1 yielded [Rh2Ru4(CO)16B{AuP(C6H11)3}]3 in two isomeric forms 3a and 3b. Similar reactions occur with other phosphine gold(I) derivatives. The crystal structure of compound 3a has been determined and reveals a trans arrangement of Rh atoms and a face capping AuP(C6H11)3 unit. The anion [Ru4H(CO)12BH]– reacted with [Ir2L4Cl2](L = cycloctene or L2= cycloocta-1,5-diene) under a stream of CO to give [Ir2Ru4(CO)16B]–2; the crystal structure of 2 has been determined and confirms an octahedral metal framework with trans iridium atoms. Cluster 2 reacted with [AuCl{P(C6H11)3}] to yield [Ir2Ru4(CO)16B{AuP(C6H11)3}]4 and crystallographic data for 4 show that the Ir atoms are mutually cis in the octahedral Ir2Ru4 skeleton. The AuP(C6H11)3 unit bridges the Ir–Ir edge. In [Ru4H(CO)12BH]–, the four ruthenium atoms define a butterfly framework with the boron atom lying in a semi-interstitial position. The addition of two Group 9 metal atoms to close up the metal cage to an octahedral one with an M2Ru4 core should initially give a cis isomer. In fact the trans isomer is observed for both 1 and 2, although for 1 both cis and trans isomers are observed by 11B NMR spectroscopy. Geometrical preferences which accompany the addition of a gold(I) phosphine fragment to anions 1 and 2 to give 3 and 4 respectively are discussed.

Optical absorption in porous silicon of high porosity

We report IR and absorption edge spectra of porous silicon (PS), covering a porosity range where the average size of the domains is comparable with the pore radius. There are two distinct IR absorption groups related to degree of specimen “aging” and porosity; these can be attributed to CH i, H(C jH i) and to SiO m, Si(OH i) bond vibrations. The last two dominate in high porosity specimens. The absorption edge spectra can be deconvoluted into a band-to-deep state absorption at ⋍ 1 eV and a parbolic band-to-band absorption, with gap E g = 1.6−2 V and an absorption shoulder at hv ⩽ E g. The optical density ofbands is significantly reduced for porosity above 70%. Optical parameters of an absorption shoulder correlate approximately with photoluminescence spectra and the strength of CH i and H(C jH i) vibrations.

Determination of the performance of edge filters containing PbTe on cooling

Optical spectra of cooled IR edge filters containing PbTe have been measured at various temperatures such as 300, 200, 150 and 100 K. Generally it will be found that the cut-on edge shifts in proportion to the temperature, while the cut-off edge remains nearly unmoved. These problems will be discussed in this paper by both experimental and theoretical analysis.

Chemistry of iridium carbonyl cluster complexes. Synthesis, chemical characterization and X-ray crystal structures of [PPh4][Ir6(CO)15Cl] · C4H8O and [PPh4][Ir6(CO)14Cl

Abstract The anion [Ir 6 (CO) 15 Cl] − has been formed by treating [Ir 6 (CO) 15 ] 2− with FeCl 3 ; [Ir 6 (CO) 15 Cl] − ( 1 ) is the first species formed, but if kept standing 1 slowly loses a CO ligand to give [Ir 6 (CO) 14 Cl] − ( 2 ). Compound 1 can also be obtained by treating Ir 6 (CO) 16 with LiCl in anhydrous tetrahydrofuran, but, because of the long reaction time needed, a substantial amount of compound 2 is also formed. The crystal structures of [PPh 4 ][Ir 6 (CO) 15 Cl] · C 4 H 8 O ( 1 ) and [PPh 4 ][Ir 6 (CO) 14 Cl] ( 2 ) have been determined. Anion 1 contains an octahedron of iridium atoms surrounded by eleven terminal, one edge, and three face-bridging carbonyl groups, and by one terminal chlorine atom. The disposition of the bridging carbonyl groups can be related to that of Ir 6 (CO) 16 (red isomer) in which one face-bridging carbonyl group has become edge bridging. Selected bond distances are: IrIr(average) 2.774, IrC(terminal, average) 1.85, IrC(edge bridging, average) 2.13, IrC(face bridging, average) 2.22, IrCl 2.395(5) A. Anion 2 contains a slightly distorted octahedron of iridium atoms bearing twelve terminal and two edge-bridging carbon monoxide groups; the chlorine atom bridges an IrIr edge. The stereochemistry of anion 2 is related to that of [Ir 6 (CO) 15 ] 2− by replacing an edge-bridging carbonyl group by the μ-halogen atom [Cl bridges Ir(4)Ir(3), C(13) bridges Ir(1)Ir(6), C(14) bridges Ir(2)Ir(3)]; i.e. each of the six iridium atoms is involved in only one bridge. Average selected bond distances are: IrIr 2.767, IrC(terminal) 1.85, IrC(edge bridging) 2.05, IrCl 2.484 A.

Tellurium halide glasses. New materials for transmission in the 8–12 μm range

A new class of IR transmitting glasses has been discovered in the binary systems TeCl and in the ternary systems TeClS, TeClSe, TeBrSe, TeBrS, TeBrSe; TeBrS and TeISe. The ternary glasses have a very high resistance towards devitrification. These so-called “TeX glasses” have a glass temperature T g ranging from 50°C to 85°C depending on the composition. The S or Cl containing glasses have their IR edge located in the 13 μm region while the compositions not containing these light elements have their multiphonoedge near 18 μm. A typical glass composition such as Te 3Br 2 has a potential high transparency of about 10 dB/km at 10.6 μm estimated from band-gap and multiphonon absorption. Samples prepared from high purity compounds show no parasitic absorption bands due to OH, SH and other complex anions. Vitreous domains, preparation conditions and some properties such as thermal expansion and resistance to corrosion by water are discussed.

Chemistry of polynuclear metal complexes with bridging carbene or carbyne ligands. Part 71. Synthesis of tungsten–iridium complexes. Crystal structures of [W2Ir(µ3-RC2R)Cl(CO)4(η-C5H5)2]·CH2Cl2and [W2Ir(µ-CR)(µ3-CR)Cl(CO)4(η-C5H5)2](R = C6H4Me-4)

In tetrahydrofuran at room temperature, the complexes [W(CR)(CO)2(η-C5H5)](R = C6H4Me-4) and [IrCl(CO)(η-C8H14)2](C8H14= cyclo-octene) afford a chromatographically separable mixture of five cluster compounds [W2Ir(µ3-RC2R)Cl(CO)4(η-C5H5)2](1), [W2Ir(µ-CR)(µ3-CR)Cl(CO)4(η-C5H5)2](2, 3, and 4, isomers), and [W2Ir2(µ4-RC2R)(µ-CO)2(CO)6(η-C5H5)2](5). The reaction between [W(CR)(CO)2(η-C5H5)] and [IrCl(CO)2(NH2C6H4Me-4)] yields a similar mixture except that (2) is absent, and a possible reason for this is discussed. The molecular structures of compounds (1) and (2) have been established by single-crystal X-ray diffraction studies. That of (1) consists of a triangle of metal atoms [W–W 2.666(1), W–Ir 2.821(1) and 2.798(1)A] with the W–W bond weakly semi-bridged by a CO ligand [W–C–O 169.1(9)°]. The alkyne RC2R adopts a µ3(η2-⊥) bonding mode, transversely bridging a W–Ir bond, and tilted so that one of the ligated carbon atoms triply bridges the metal triangle [µ3-C–Ir 2.05(1), µ3-C–W 2.24(1) and 2.28(1)A]. The tungsten and iridium atoms of the W–Ir bond transversely bridged by the alkyne are, respectively, co-ordinated by Cl and C5H5, and by two CO groups. The other tungsten atom, carrying the semi-bridging CO ligand, is ligated by a CO and a C5H5 group. Compound (2) also has a triangular core [W–W 2.951(1), W–Ir 2.867(1) and 2.698(1)A]. One of the p-tolylmethylidyne ligands caps the metal triangle [µ3-C–W 2.04(2) and 2.07(2), µ3-C–Ir 2.19(2)A] while the other bridges the shorter W–Ir edge [µ-C–W 1.90, µ-C–Ir 2.06(2)A]. The tungsten atom of this edge carries a CO group and a C5H5 moiety. The other tungsten atom is ligated by Cl, CO, and C5H5 groups. Two CO ligands are co-ordinated to the iridium. The molecular structures of the isomers of (2), compounds (3) and (4), have been assigned from consideration of their n.m.r. spectra (1H and 13C-{1H}) and by comparison with those of complex (2) and a PPh3 derivative [W2Ir(µ-CR)(µ3-CR)Cl(CO)3(PPh3)(η-C5H5)2] of (4) shown to contain an Ir(CO)(PPh3) group. Like (2), complexes (3) and (4) have µ-CR, µ3-CR, and terminal W–Cl groups. However, in (3) the µ-CR ligand bridges a W–W bond and there is an Ir(CO)3 group present, whereas (4) is structurally very similar to (2) differing only in the site of the terminal Cl atom and a CO group. The spectroscopic data (i.r. and 1H and 13C-{1H} n.m.r.) for the tetranuclear cluster (5) are discussed and its structure can be assigned on the basis of an earlier synthesis.

Synthesis and chemical characterization of the hexanuclear anions [Ir6(CO)14X]–(X = Cl, Br, I, or SCN). Crystal and molecular structures of [PPh4][Ir6(µ-CO)2(CO)12(µ-Br)] and [N(PPh3)2][Ir6(µ-CO)12(µ-X)](X = I or SCN)

The salts of the monosubstituted hexanuclear anions [Ir6(CO)14X]–[X = Cl (1), Br (2), I (3), or SCN (4)] have been prepared by treating [Ir6(CO)16] with halides or pseudohalides at room temperature in tetrahydrofuran solution. Complex (2) crystallizes in the monoclinic space group P21/c(no. 14) with a= 12.653(4), b= 25.566(10), c= 13.351(2)Å, β= 91.04(2)°, and Z= 4, (3) crystallizes in the monoclinic space group P21/c(no. 14) with a= 17.444(3), b= 14.791(3), c= 23.332(5)Å, β= 113.32(2)°, and Z= 4, and (4) crystallizes in the monoclinic space group P21(no. 4) with a= 9.441(3), b= 36.952(9), c= 15.663(4)Å, β= 91.44(2)°, and Z= 4. The three structures have been solved by conventional Patterson and Fourier methods and refined by full-matrix least-squares to final conventional R values of 0.029 (2), 0.036 (3) and 0.045 (4) on the basis of 4 223, 5 427, and 7 181 independent counter data having I > 3σ(I). The three anions consist of slightly distorted octahedra of iridium atoms bearing twelve terminal and two edge-bridging carbon monoxide groups. In all cases the halogen atoms or the pseudohalogen group adopt a bridging co-ordination on an Ir–Ir edge.

Optical absorption characteristics of neutron irradiated heavy metal fluoride glasses

Samples of ZBLA and HBLA glasses were subjected to various fluences of neutron irradiation, and the spectral dependence of optical absorption was measured before and after irradiation. The IR edge was found to be unaffected by neutron irradiation for the fluences used. However, a red shift occurred at the UV edge which slightly recovered after three weeks.

Influence of processing conditions on IR edge absorption in fluorohafnate and fluorozirconate glasses

The influence of processing conditions on the IR absorption edge of fluoride glasses with the composition 62 MF4 1b 33 BaF 2 1b 5 LaF 3 (M = Hf or Zr) is reported. At higher values of the absorption coefficient ( α > 1 cm −1), the IR edge is nearly independent of processing conditions and appears to be intrinsic. At lower values ( α < 1cm −1) extrinsic features attributed to oxide impurities appear; these are suppressed when glass melting is carried out in a reactive atmosphere of CCl 4. Comparison of our results for HfF 4- and ZrF 4 based glasses shows that substitution of HfF 4 for ZrF 4 shifts the IR edge to longer wavelengths, but the intrinsic absorption curves are nearly parallel over the frequency range investigated.

Composition dependence of infrared edge absorption in ZrF 4 and HfF 4 based glasses

A set of semi-empirical criteria have been developed to assess the contribution of various components to IR edge absorption in multi-component solids. These have been applied to ZrF 4 and HfF 4 based glasses and verified experimentally. Results indicate that monovalent cation fluorides no lighter than NaF, divalent cation fluorides no lighter than CaF 2, trivalent cation fluorides no lighter than LaF 3 and quadrivalent cation fluorides no lighter than ThF 4 contribute negligibly to IR edge absorption in such glasses.