Showing papers on "Dielectric published in 1992"
TL;DR: By varying the dielectric environment in new layer-type perovskite compounds, Wang et al. as mentioned in this paper demonstrated directly the contribution by dielectrics confinement to the exciton binding energy in three such ''natural-quantum-well'' semiconductors.
Abstract: By varying the dielectric environment in new ${\mathrm{PbI}}_{4}$-based layer-type perovskite compounds, we have demonstrated directly the contribution by dielectric confinement to the exciton binding energy in three such ``natural-quantum-well'' semiconductors. With different dielectric environment, exciton binding energies of 320, 220, and 170 meV have been observed, dominated by the dielectric confinement. In terms of the conventional size-related electronic confinement, two of the materials represent monolayer ${\mathrm{PbI}}_{4}$ quantum wells while the third corresponds to a bilayer case, with a corresponding reduction in the electronic confinement. From theory, including the dielectric confinement effect, the effective mass of the exciton in a ${\mathrm{PbI}}_{4}$-based dielectric quantum well has been determined to be 0.09${\mathit{m}}_{\mathit{e}}$; the corresponding quasi-two-dimensional exciton Bohr radii were 15.5, 17.0, and 20.5 \AA{} for the three cases, respectively.
623 citations
Proceedings Article•
10 May 1992TL;DR: The contribution by dielectric confinement to the exciton binding energy in three such ``natural-quantum-well'' semiconductors has been demonstrated directly, dominated by the dielectrics.
Abstract: Optical properties of excitons in conventional semiconductor quantum-well structures derive from the spatial confinement of electrons and holes by variations in the electronic potential across the barrier and the well layers. However, a barrier layer with a smaller dielectric constant can substantially increase the binding energy of excitons in the well, especially when the dielectric constant in the barrier layer is sizably smaller than that in the well layer (eb < ew). Theory suggests that the binding energy of excitons in the well can substantially exceed the value of four-exciton Rydbergs, the ideal limit of the conventional two-dimensional (2D) system.
434 citations
TL;DR: In this paper, the state-of-the-art for induced and spontaneous polarization in real materials is presented, both for spontaneous and induced polarization, and for the latter case, a novel approach is proposed.
Abstract: Contrary to common textbook statements, the macroscopic electric polarization of a crystal cannot be unambiguously defined as the dipole of a unit cell. The only measurable quantities are either derivatives of the polarization (dielectric susceptibility, Born effective charges, piezoelectricity, pyroelectricity) or finite differences (ferroelectricity). The differential concept is a basic one in theoretical work too. I sketch here the basic theory and the state of the art in its implementation to real materials, both for induced and spontaneous polarization; for the latter case, I also propose a novel approach.
374 citations
TL;DR: In this paper, complex dielectric permittivities of CH3NH3PbX3 (X = Cl, Br, I) were measured at frequencies between 20 Hz and 1 MHz and at temperatures between 20 and 300 K (15 and 350 K for the iodide).
356 citations
TL;DR: In this paper, a two-dimensional periodic dielectric structure that has a complete inplane photonic band gap for both polarizations was identified, and a triangular lattice of air columns was found to have the desired band gap properties.
Abstract: A systematic theoretical investigation is undertaken in order to identify a two‐dimensional periodic dielectric structure that has a complete in‐plane photonic band gap for both polarizations. Of the various structures studied, only a triangular lattice of air columns is found to have the desired band‐gap properties. Microwave transmission experiments are performed to test the theoretical predictions.
330 citations
TL;DR: In this article, forces between particles aligned into chains by an applied electric field in an electrorheological (ER) fluid are calculated using finite element techniques and, approximately, using a dipole approximation with local field effects.
Abstract: Forces between particles aligned into chains by an applied electric field in an electrorheological (ER) fluid are calculated using finite‐element techniques and, approximately, using a dipole approximation with local‐field effects. Evaluation of the effective dielectric constant is emphasized and the shear modulus is derived from the shear dependence. For high‐frequency (f≳0.1–1 kHz) applied electric fields, the forces and the modulus depend upon the dielectric constants of the suspending fluid and the dispersed particles. For low‐frequency or dc electric fields, the conductivities of the components are dominant. These effects are treated within a Maxwell–Wagner approach. If the ratio of particle‐to‐fluid conductivities substantially exceeds the ratio of dielectric constants, a large enhancement of the modulus is found. Implications for the design of ER fluids are discussed briefly.
318 citations
TL;DR: The photonic band strucfure in a two-dimensional dielectric array is investigated using the coherent microwave transient spectroscopy (COMITS) technique and the experimental results are compared with theoretical predictions obtained using the plane-wave expansion technique.
Abstract: The photonic band structure in a two-dimensional dielectric array is investigated using the coherent microwave transient spectroscopy (COMITS) technique. The array consists of alumina-ceramic rods arranged in a regular square lattice. The dispersion relation for electromagnetic waves in this photonic crystal is determined directly using the phase sensitivity of COMITS. The experimental results are compared to theoretical predictions obtained using the plane-wave expansion technique. Configurations with the electric field parallel and perpendicular to the axis of the rods are investigated.
304 citations
TL;DR: This issue is investigated by studying a model polymer, the HCl-doped emeraldine salt from of oriented polyaniline (PAN-ES), through the temperature dependence of the dc conductivity, thermoelectric power, complex microwave dielectric constant, EPR, and electric-field dependence of conductivity.
Abstract: It is an open question if ``metallic'' polymers have one-dimensional or three-dimensional conduction states. We investigate this issue by studying a model polymer, the HCl-doped emeraldine salt form of oriented polyaniline (PAN-ES) through the temperature dependence of the dc conductivity, thermoelectric power, complex microwave dielectric constant, electron paramagnetic resonance (EPR), and electric-field dependence of conductivity. The thermopower, microwave dielectric constant, and EPR data suggest that the electrons are three dimensionally delocalized. We propose that oriented PAN-ES consists of coupled parallel chains that form ``metallic'' bundles. These bundles are the ``crystalline'' regions of the polymer in which the electron wave functions are three dimensionally extended. This is in contrast to conventional quasi-one-dimensional conductors (many ``metallic'' charge-transfer salts) in which conducting chains are essentially isolated. However, between bundles are the amorphous (less-ordered) regions in which charge hopping dominates the macroscopic conductivity. The formation of the ``metallic'' bundles is proposed to be the result of a significant charge-interchain-transfer rate inside the crystalline regions. The implications of the results for the improvement of conductivity are addressed.
303 citations
TL;DR: In this article, a dielectric function model yielding a Gaussian shape of the absorption lines and satisfying Kramers-Kronig relations was suggested for modeling of infrared spectra.
Abstract: For the modeling of infrared spectra it is a common approach to use a dielectric function that treats the vibrational modes as damped harmonic oscillators. This model was found to be rather crude for some applications to amorphous solids. A dielectric function model yielding a Gaussian shape of the absorption lines and satisfying Kramers–Kronig relations is suggested. The model function is constructed by a convolution of a Gaussian function with the dielectric function of the damped harmonic oscillator model. An analytical solution of this integral is given. It is demonstrated that this model describes the spectra of thermally grown ultrathin (1.3 nm) silicon oxide films, plasma‐deposited silicon films, plasma‐deposited silicon nitride films, and amorphous aluminum oxide films very well. The physical motivation of the dielectric function model suggested is the randomness of the vibrational frequencies in an amorphous structure.
300 citations
TL;DR: In this paper, the authors analyzed the operation of high-reflectivity quarter-wave (QW) dielectric mirrors at the bandstop center (Bragg) frequency, relevant for the design of small-cavity optoelectronic structures.
Abstract: The authors analyze the operation of high-reflectivity quarter-wave (QW) dielectric mirrors at the band-stop center (Bragg) frequency, relevant for the design of small-cavity optoelectronic structures. The energy penetration depth concept is used to determine a first-order linear approximation for the reduction of the mirror peak reflectivity of the QE mirror as a function of the mirror material parameters and the number of layers. The expression can be applied in the limit of small loss. The mathematical analysis and expressions for the absorptance and the peak reflectivity of a dielectric mirror with weak material absorption are presented. The use of the results is illustrated for a typical vertical cavity surface-emitting laser structure. >
300 citations
IBM1
TL;DR: It is shown that first-principles electronic structure calculations of silicon wires with diameters up to 1.5 nm support the idea that quantum confinement and surface effects are responsible for the luminescence in porous silicon.
Abstract: We show that first-principles electronic structure calculations of silicon wires with diameters up to \ensuremath{\sim}1.5 nm support the idea that quantum confinement and surface effects are responsible for the luminescence in porous silicon. Instead of the indirect gap of crystalline bulk silicon, the band structure of these wires exhibits a direct gap at k=0. The imaginary part of the dielectric function, polarized in the direction of the wire, shows a peak in the visible range. The dependence of this feature on wire size is analyzed and correlated to experimental luminescence spectra.
Patent•
23 Apr 1992
TL;DR: Antifuses and gate arrays with antifuses are disclosed that have high thermal stability, reduced size, reduced leakage current, reduced capacitance in the unprogrammed state, improved manufacturing yield, and more controllable electrical characteristics as mentioned in this paper.
Abstract: Antifuses and gate arrays with antifuses are disclosed that have high thermal stability, reduced size, reduced leakage current, reduced capacitance in the unprogrammed state, improved manufacturing yield, and more controllable electrical characteristics. Some antifuses include spacers in the antifuse via. In some antifuses, the programmable material is planar, and the top or the bottom electrode is formed in the antifuse via. In some gate arrays, the antifuses are formed above the dielectric separating two levels of routing channels rather than below that dielectric.
TL;DR: In this article, the dielectric properties of several bismuth-based ceramics at microwave frequencies were investigated and the crystal structure of this composition was considered to be an ordered structure based on the body center tetragonal cell (a=0.377, c=0,542 nm).
Abstract: We have investigated dielectric properties of several bismuth-based ceramics at microwave frequencies. BiNbO4 ceramics containing CuO and V2O5, had a high Q value of Q=4260 (at 4.3 GHz), e=43, and τf=+38 ppm/°C. In the Bi2O3-CaO-Nb2O5 system, Bi18Ca8Nb12O65 composition had a high dielectric constant of e=59, Q=610 (at 3.7 GHz), and τf=+24 ppm/°C. The crystal structure of this composition is considered to be an ordered structure based on the body center tetragonal cell (a=0.377, c=0.542 nm). Furthermore, by substituting Zn for Ca, e increased and τf changed to negative values. In the composition of 45.75BiO3/2-21.75(Ca0.725Zn0.275)O-32.5NbO5/2, excellent properties of e=79, Q=360 (at 3.3 GHz), and τf=+1 ppm/°C were obtained. As all the above ceramics can be sintered below 950°C, they are applicable to multilayer microwave devices with Ag inner conductors.
TL;DR: The electric field at the amino terminus of an alpha helix in water has been determined by measuring the shift in the absorption band for a covalently attached, neutral probe molecule with an electric dipole moment difference between the ground and excited electronic states.
Abstract: The strengths of electrostatic interactions in biological molecules are difficult to calculate or predict because they occur in complicated, inhomogeneous environments. The electric field at the amino terminus of an alpha helix in water has been determined by measuring the shift in the absorption band for a covalently attached, neutral probe molecule with an electric dipole moment difference between the ground and excited electronic states (an internal Stark effect). The field at the interface between the helix and the solvent is found to be an order of magnitude stronger than expected from the dielectric properties of bulk water. Furthermore, although the total electric dipole moment of the helix increases with length, the electric field at the amino terminus does not.
TL;DR: The role of zinc oxide as a sintering aid and lanthanum and niobium as dopants, their effect upon microstructural development and their correlation with dielectric loss at microwave frequencies were investigated in this article.
Abstract: Ceramics with compositions in the solid solution region of the ZrO2-TiO2-SnO2 equilibrium diagram are finding wide application as dielectrics in filters for communications and radar systems operating at microwave frequencies. Commercially available compositions often incorporate sintering aids and dopants to reduce processing temperatures and modify the dielectric properties. However, the mechanism through which these additives influence dielectric loss is not obvious. The role of zinc oxide as a sintering aid and lanthanum and niobium as dopants, their effect upon microstructural development and their correlation with dielectric loss at microwave frequencies were investigated. For specimens of density greater than 90% theoretical, the influences of defect chemistry upon dielectric loss appear to dominate those of the microstructure. Properties close to those which might be considered intrinsic were attained through sintering for periods of up to 128h. Doping with lanthanum is detrimental to the dielectric loss, particularly after long sintering times.
TL;DR: In this paper, the authors used a simple model for electronic hopping through the PZT lead zirconate titanate (PZT) film to obtain a leakage current as low as 9*10/sup -8/ A/cm/sup 2/ at 2.5 V for a 4000-AA film with the addition of La and Fe to compensate for Pb and O vacancies.
Abstract: Ferroelectric lead zirconate titanate (PZT) films with as much as 2.5 times the storage capacity of the best reported silicon oxide/nitride/oxide (ONO) stacked dielectrics have been fabricated. A 2000-AA film with an effective SiO/sub 2/ thickness of 10 AA is demonstrated. Because of the extremely high dielectric constant ( epsilon /sub r/>or approximately=>1000), even larger storage capacities can be obtained by scaling the ferroelectric film thickness, whereas the thickness of ONO films is limited by direct tunneling through the film. Electrical conduction in the PZT films studied is ohmic at electric fields below 250 kV/cm and follows an exponential field dependence at higher fields, which is shown to be consistent with a simple model for electronic hopping through the film. Leakage current as low as 9*10/sup -8/ A/cm/sup 2/ at 2.5 V for a 4000-AA film is obtained with the addition of La and Fe to compensate for Pb and O vacancies in the film. Further improvement in both leakage current and time-dependent dielectric breakdown characteristics are necessary to ensure reliable DRAM operation. >
TL;DR: This paper surveys the following topics, concentrating on contributions from the laboratory:Linear properties of electrode polarization and relevant modelsEffects of electrodes polarization on sample impedanceEffects of sample on polarization impedanceTechniques of correctionExtension of linear to nonlinear modelsHarmonics generated in the nonlinear range.
Abstract: Electrode polarization is a major nuisance while determining dielectric properties of cell and particle suspensions and tissues, particularly at low frequencies. Understanding of these interfacial phenomena and appropriate modelling are essential in order to correct for its distortion of the dielectric properties of the sample of interest. I survey the following topics, concentrating on contributions from our laboratory: Linear properties of electrode polarization and relevant models. Effects of electrode polarization on sample impedance. Effects of sample on polarization impedance. Techniques of correction. Extension of linear to nonlinear models Harmonics generated in the nonlinear range.
TL;DR: It is concluded that the dielectric relaxation of tissue water is not the only dispersive process occurring at this frequency: dielectrics relaxation of bound water and the tail end of a beta-dispersion may also contribute to the dielection properties.
Abstract: Complex permittivities of in vitro diseased and undiseased human female breast tissues have been measured at 3.2 GHz using a resonant cavity technique. Ranges of dielectric properties and water contents of these tissues are presented. Experimental data are compared with models predicted from mixture equations. Measured permittivity data lie within limits set by two-phase mixture theory, but some conductivity data are in excess of those expected for a mixture of saline and protein. At any particular microwave frequency in all tissue of a given type, the relationship between permittivity and conductivity may be parametrized using the Debye relaxation equations. For each breast tissue type a characteristic relaxation frequency was calculated and found to be lower than that of physiological saline at the same temperature. It is concluded that the dielectric relaxation of tissue water is not the only dispersive process occurring at this frequency: dielectric relaxation of bound water and the tail end of a beta-dispersion may also contribute to the dielectric properties. The similarity of the dielectric properties of benign and malignant breast tumours measured in this work suggest that in vivo dielectric imaging methods will not be capable of distinguishing them.
TL;DR: In this article, Hartree-Fock force fields for molecular dynamica simulations of poly(viny1idene fluoride), PVDF, were used to predict structure and properties of nine stable structures of polyvinyl fluoride (PVDF) crystals including four experimentally observed forma plus a fifth crystal form suggested by Lovinger.
Abstract: We report two new force fields for molecular dynamica simulations of poly(viny1idene fluoride), PVDF. The first, MSXX, was obtained with Hartree-Fock calculations of 1,1,1,3,3-pentafluorobutane plus experimental frequencies of the form I, crystal. The second, the covalent shell model (MSXXS), waa developed to also account for polarization. These force fields were used to predict structure and properties of nine stable structures of poly(viny1idene fluoride) crystals including the four experimentally observed forma plus a fifth crystal form suggested by Lovinger. In each case we used the force field to establish that the structure is mechanically stable and to predict cell parameters, elastic constants, dielectric constants, and piezoelectric constants.
TL;DR: In this article, a spincoating technique was used to obtain thin Pb(ZrxTi1−x)O3 films with zirconium concentrations ranging from x=0.2 to 0.75.
Abstract: The deposition of thin Pb(ZrxTi1−x)O3 films by sol‐gel and by metallo‐organic decomposition (MOD) processes has been studied. Powders obtained from different precursor solutions were analyzed with respect to their decomposition and crystallization. Using a spin‐coating technique, Pb(ZrxTi1−x)O3 films with zirconium concentrations ranging from x=0.2 to 0.75 have been deposited on Pt‐electroded Si wafers. The lattice constants of the perovskite films and their dielectric and ferroelectric properties (permittivity, remanent polarization, coercive field strength) have been measured as a function of the zirconium concentration. The results are compared to the data obtained on bulk ceramics. For Pb(ZrxTi1−x)O3 films with a composition located at the morphotropic phase boundary (x≊0.53) the influence of the processing and the lead excess of the starting solutions on the film properties was examined. First measurements on the resistance degradation of thin Pb(Zr0.53Ti47)O3 films deposited by the MOD process are r...
TL;DR: In this article, a reformulation of reference interaction site model theory is proposed, which makes use of the formally correct asymptotic form of the correlations obtained from the one-center angular expansion technique.
TL;DR: The polarization behavior of La-modified lead zirconate titanate relaxors has been investigated for various electrical and thermal histories and the magnitude of both polarizations were found to be equal above a critical temperature.
Abstract: The polarization behavior of La-modified lead zirconate titanate relaxors has been investigated for various electrical and thermal histories. The field-cooled and zero-field-cooled behaviors were both studied. The magnitude of both polarizations were found to be equal above a critical temperature. A macroscopic polarization developed, when the zero-field-cooled state was warmed with a bias applied. The temperature of the maximum charging current decreased with increasing bias field. This decrease was modeled using the deAlmeida-Thouless relationship [J. deAlmeida and D. Thouless, J. Phys. A 11, 983 (1978)], which predicted an average moment size freezing of approximately 3\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}27}$ C m. A glassy polarization mechanism was subsequently proposed with correlations between superparaelectric moments leading to the development of effective nonergodicity in a frozen state. Arguments are presented that this freezing process is dispersive due to a distribution of correlation strengths. The time dependence of the polarization was also investigated.
TL;DR: In this article, the static and dynamic yield stresses in an electrorheological (ER) fluid were derived from a microstructural model and the model relates both these yield stresses to the electrostatic energy determined from the suspension capacitance matrix.
Abstract: We describe and determine the static and dynamic (Bingham) yield stresses in an electrorheological (ER) fluid from a microstructural model. The model relates both these yield stresses to the electrostatic energy determined from the suspension capacitance matrix, which we developed previously for the dynamic simulation of an ER fluid. The static yield stress is determined from nonlinear elasticity strain‐energy theory applied to an ER fluid for a variety of volume fractions and particle‐to‐fluid dielectric constant ratios. The static yield stress increases with the dielectric constant ratio and exhibits a maximum at 40 Vol % particles for dielectric constant ratios of 4 or less. From the capacitance of the suspension we also compute the zero‐frequency birefringence of the ER fluid and show that it follows a nonlinear stress‐optical rule. The dynamic yield stress, as we have observed in our previous simulations, dominates the rheology of the ER fluid at large electric field strengths. At the same time the e...
Patent•
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IBM1
TL;DR: In this article, a package for mounting I/C chips onto a circuit board is described, where the chip has a surface array of input/output pads on one side which forms a footprint.
Abstract: A package for mounting I/C chips onto a circuit board is provided. The chip has a surface array of input/output pads on one side which forms a footprint. A carrier is formed of an organic dielectric material having opposite surfaces. A first set of bonding pads is formed on one surface of the chip carrier and arranged to correspond with the chip footprint. A first set of solder ball connections connects the input/output pads on the chip to the first set of bonding pads on the chip carrier. A second set of bonding pads is formed on the other surface of the chip carrier forming a second set of bonding pads. Electrically conducting vias extend through the chip carrier connecting the first set of bonding pads to the second set of bonding pads. An organic circuit board having a coefficient of thermal expansion similar to the chip carrier having electrical connector sites is provided, the sites are arranged in a pattern corresponding to the pattern of the second bonding pads on the chip carrier. A second set of solder ball connections connect the pads of the second set of bonding pads on the chip carrier to the connection sites on the circuit board.
TL;DR: In this article, the authors discuss electrostatic stabilization of dispersions in non-aqueous media, with particular attention to the roles of the dielectric constant and ionic strength of the liquid medium.
TL;DR: In this article, the relationship between the refractive index and number of ions/unit volume (N/V) with polarizability α has been discussed, and the reduced number of polarizable ions per unit volume was primarily responsible for the reduction in the dielectric constant.
Abstract: The refractive index for a family of optical glasses (tellurite containing halide) has been analyzed. From the dielectric theory, the relationship between the refractive index and number of ions/unit volume (N/V) with polarizability α has been discussed. Halogen substitution resulted in a lower dielectric constant, along with lower density and lower refractive index. The reduced number of polarizable ions per unit volume was primarily responsible for the reduction in the dielectric constant, although reductions in electronic polarization also affected the dielectric properties.
TL;DR: In this paper, a subcell model for thin material sheets in the finite-difference time-domain method is presented, which leads to greatly reduced storage requirements and a corresponding reduction in the number of time steps needed.
Abstract: A subcell model is presented for including thin material sheets in the finite-difference time-domain method. The subcell model removes the normal restriction which sets the spatial grid increment at least as small as the smallest physical feature in the solution space. Removing this restriction leads to greatly reduced storage requirements and a corresponding reduction in the number of time steps needed. The subcell model is verified by comparison with the exact results for the loss and phase shift for a parallel plate waveguide loaded with a thin material sheet. Specifically, thin conducting as well as thin dielectric sheets are investigated for both TEM and TM/sub 1/ time-harmonic excitations of the waveguide. The FDTD results are in very good agreement with the exact results. Finally, the subcell model is used in the analysis of a practical problem-a resistively loaded monopole antenna formed from a thin-walled conducting tube. The FDTD results are compared with accurate measurements for this antenna, and, again, the two are in very good agreement. >
TL;DR: In this paper, the effects of charged clay platelets on the frequency dependent electrical properties of shaly materials are analyzed using simplified models for the membrane polarization around charged spheres immersed in electrolytic solutions, under a thin double layer approximation.
Abstract: The effects of charged clay platelets on the frequency dependent electrical properties of shaly materials are analyzed using simplified models for the membrane polarization around charged spheres immersed in electrolytic solutions, under a thin double layer approximation. The polarization is defined through two possible mechanisms: (1) a surface conductivity related with a modified Stern double layer model (S-model) according to Schurr-Schwarz theory; (2) a coupled electro-diffusional mechanism occurring in a Guoy-Chapman double layer using Fixman's approach (D-model). By comparing the electric potential in such microscopic models with the external potentials derived for the equivalent homogeneous sphere using a Maxwell-Wagner approach, we obtain the total current conductivity functions for these two models. The theory, therefore, provides explicit expressions relating the total conductivity functions to the model parameters.The behavior of the S-model is described by a complex conductivity exhibiting a simple Debye characteristic. In the D-model, both the conductivity and the dielectric permittivity are given as complex properties, showing similar but much wider dispersion than that of a Debye substance. Our representation of the grains and their associated ionic double layers by an equivalent sphere with effective properties allows us to extend our results to simulate rocks containing clays. This is accomplished using generalized mixture equations written in terms of the total conductivity functions. The frequency behavior of both models are compared and their fit to experimental data on clay-water systems and shaly materials suggest that the D-model is more appropriate for representing the dielectric behavior of clay bearing rocks. The theory can be adapted to estimate the clay parameters of a shaly sandstone using electromagnetic borehole measurements.
TL;DR: In this article, the scattering of an incident plane wave from an array of parallel circular dielectric and/or conducting cylinders is derived rigorously using a boundary value approach using both transverse electric (TE) and transverse magnetic (TM) polarized incident plane waves.
Abstract: The scattering of an incident plane wave from an array of parallel circular dielectric and/or conducting cylinders is derived rigorously using a boundary value approach. Both transverse electric (TE) and transverse magnetic (TM) polarized incident plane waves are considered. The validity and accuracy of the method are verified by comparing the numerical results with those based on other available methods. The advantage of the proposed analysis is the simplicity and efficiency in computation. The modeling of two-dimensional objects of arbitrary cross section and composite material is outlined and sample numerical results are presented to illustrate the versatility of the method. >
TL;DR: This work has calculated the effect of material absorption on the rate of spontaneous emission by an embedded atom using a macroscopic Green-function approach and a microscopic Hamiltonian method that includes reservoir damping.
Abstract: We have calculated the effect of material absorption on the rate of spontaneous emission by an embedded atom using a macroscopic Green-function approach and a microscopic Hamiltonian method that includes reservoir damping. When local field effects are neglected, the free-space emission rate is modified by the real part of the refractive index at the transition frequency of the embedded atom. Local field effects are introduced via a local field correction factor. This modification of the spontaneous emission rate generalizes a well-known result for transparent media and is of crucial importance in assessing the degree of inhibition of spontaneous emission for frequencies close to the resonances of the dielectric.