Showing papers on "Photoluminescence published in 1989"
TL;DR: In this paper, a list of published photoluminescence transitions indicating their key properties is presented. And the relationship between the excited states of some optical centres and the band states of the silicon host lattice is discussed.
449 citations
CNET1
TL;DR: In this paper, the luminescence of erbium implanted in various semiconductors such as Si, InP, GaAs, AlGaAs, GaInAsP, ZnTe and CdS is presented.
Abstract: Luminescence of erbium implanted in various semiconductors such as Si, InP, GaAs, AlGaAs, GaInAsP, ZnTe and CdS is presented. The Er/sup 3+/ emission wavelength is the same for all these semiconductors with a bandgap energy greater than the intrashell transition energy of Er 4f electrons (0.805 eV). The Er/sup 3+/ emission intensity depends strongly on both the bandgap energy of the host semiconductor and the material temperature. To obtain an intense room temperature emission, a wide-gap semiconductor must be used.
420 citations
TL;DR: In this article, a photoluminescence study of an (AlGa)As-GaAs quantum-well-wire array directly grown by molecular-beam epitaxy on a tilted substrate is described.
Abstract: A photoluminescence study of an (AlGa)As-GaAs quantum-well-wire array directly grown by molecular-beam epitaxy on a tilted substrate is described. A strong anisotropy was observed in the ratio of the electron-light-hole-exciton peak intensity to the electron-heavy-hole-exciton peak intensity. A theory incorporating the optical selection rule for two-dimensional quantum confinement is found to agree very well with the measured data. These results constitute the first evidence of two-dimensional quantum confinement in artificial wire structures having cross-sectional dimensions in the nanometer range.
282 citations
TL;DR: In this article, the authors examined the optoelectronic properties of Ga0.5In 0.5P/GaAs double heterostructures grown by organometallic chemical vapor deposition.
Abstract: Using time‐resolved photoluminescence, we have examined the optoelectronic properties of Ga0.5In0.5P/GaAs/Ga0.5In0.5P double heterostructures grown by organometallic chemical vapor deposition. For comparison, similar structures using Al0.4Ga0.6As/GaAs and Al0.5In0.5P/GaAs lattice‐matched heterointerfaces were also examined. For the Ga0.5In0.5P/GaAs heterostructure, we show that the recombination velocity at a Ga0.5In0.5P/GaAs interface can be less than 1.5 cm/s. As a result, photoluminescence decay times as long as 14 μs have been observed in undoped GaAs double heterostructures. This photoluminescence decay time varies with temperature as T1.59, characteristic of radiative recombination not limited by surface or bulk nonradiative recombination processes. For the Al0.4Ga0.6As/GaAs and Al0.5In0.5P/GaAs heterostructures examined in this study, the upper limits of the interface recombination velocity were 210 and 900 cm/s, respectively.
263 citations
TL;DR: Observation of the decay lifetime of photoluminescence and calculations using the ab initio molecular-orbital program show that the 7.6-eV band is caused by a singlet-to-singlet transition, while the 5.0-ev band is cause by a singslet- to-triplet transition.
Abstract: Various uv and vacuum-uv optical-absorption bands found in as-manufactured high-purity ${\mathrm{SiO}}_{2}$ glass were studied. Two types of absorption bands were found near 5.0 eV, one of which is attributed to the oxygen vacancy (?Si-Si?). The absorption band at 7.6 eV is also found to be caused by the same oxygen vacancy. Observation of the decay lifetime of photoluminescence and calculations using the ab initio molecular-orbital program show that the 7.6-eV band is caused by a singlet-to-singlet transition, while the 5.0-eV band is caused by a singlet-to-triplet transition.
262 citations
230 citations
TL;DR: The phase relaxation of two-dimensional (2D) heavy-hole excitons in a 12-nm GaAs single quantum well subjected to collisions with either free carriers or incoherent heavy- holes is investigated by time-resolved degenerate four-wave mixing.
Abstract: The phase relaxation of two-dimensional (2D) heavy-hole excitons in a 12-nm GaAs single quantum well subjected to collisions with either free carriers or incoherent heavy-hole excitons is investigated by time-resolved degenerate four-wave mixing. The homogeneous linewidth corresponding to the phase coherence time reveals a collisional broadening due to exciton-exciton scattering and an 8 times stronger exciton-free carrier scattering. Both scattering processes are enhanced for 2D excitons as compared to 3D excitons.
184 citations
TL;DR: In this paper, the band-gap narrowing of GaAs as a function of doping concentration has been measured using photoluminescence spectroscopy on samples grown by molecular beam epitaxy.
Abstract: Band‐gap narrowing of GaAs as a function of doping concentration has been measured using photoluminescence spectroscopy on samples grown by molecular beam epitaxy. Both n‐ (Si) and p‐ (Be) doped samples with concentrations varying from 3×1017 to 3×1018 cm−3 have been measured. The experimental results obtained from a line‐shape analysis of the spectra taking tailing effects into account are in good agreement with recent theoretical calculations. A simple expression for the band‐gap narrowing as a function of concentration for both n‐and p‐doped GaAs is given.
157 citations
TL;DR: In this paper, the structural and electronic properties of hydrogenated amorphous silicon-germanium alloys deposited by rf glow discharge from SiH4 and GeH4 in a diode reactor were investigated.
Abstract: We report on a detailed study of structural and electronic properties of hydrogenated amorphous silicon‐germanium alloys deposited by rf glow discharge from SiH4 and GeH4 in a diode reactor. The chemical composition of the alloys is related to the deposition conditions, with special emphasis on preferential incorporation of Ge into the solid phase and on the role of inert dilutant gases. Hydrogen bonding in the alloys is investigated with nuclear magnetic resonance and vibrational (Raman and infrared) spectroscopy. The optical properties of a‐SiGe:H samples deposited under optimal conditions are analyzed with the help of subgap absorption measurements and band‐tail luminescence for the entire range of alloy composi‐tions. A large part of the article describes an investigation of the electron‐spin‐resonance response of undoped alloys. The spin density associated with dangling bond defects localized on Si and Ge atoms has been measured as a function of alloy composition for optimized material. In addition, ...
132 citations
TL;DR: In this article, the excitation and quenching mechanism of intra-4f-shell luminescence of Yb ions incorporated in an InP host is discussed based on experimental results of photoluminescence excitation spectra.
Abstract: The excitation and quenching mechanism of intra‐4f‐shell luminescence of Yb ions incorporated in an InP host is discussed. The discussion is based on experimental results of photoluminescence excitation spectra and photoluminescence time‐decay curves for crystals grown by metalorganic chemical vapor deposition and liquid‐phase epitaxy. The present as well as previously reported experimental results for samples grown by various methods can be consistently interpreted by considering a recently reported Yb‐related acceptorlike electron trap near the conduction‐band edge and by taking into account the shallow donor and acceptor as well as Yb concentrations in the samples. A model is proposed which describes the Yb intra‐4f‐shell excitation and quenching mechanisms for samples with various concentrations of the impurities.
121 citations
TL;DR: In this paper, a series of strained single quantum well structures was fabricated with zinc-blende MnTe forming the barrier to CdTe quantum well regions; photoluminescence spectra indicate optical transitions corresponding to strong electron and hole confinement.
Abstract: Epilayers of the previously hypothetical zinc‐blende MnTe have been grown by molecular beam epitaxy. Epitaxial layers (0.5 μm thick) of MnTe were characterized using x‐ray diffraction and transmission electron microscopy; optical reflectance measurements indicate a band gap of ∼3.2 eV. A series of strained single quantum well structures was fabricated with zinc‐blende MnTe forming the barrier to CdTe quantum well regions; photoluminescence spectra indicate optical transitions corresponding to strong electron and hole confinement.
TL;DR: In this paper, a model based on the thin film solution of Fick's second law was proposed to quantify the dynamics of ion motion which produces the green dimer emission band.
Abstract: : The luminescence spectra of copper(+) doped sodium(+) Beta alumina single crystals reveal emission bands due to both Cu(+) monomers and Cu(+) - Cu(+) dimers. At low temperature two monomer emissions (410 nm and 440 nm) and two dimer emissions (515 nm and 540 nm) are observed. These bands are assigned to ions in specific sites within the Beta alumina conduction plane. The relative intensities of the emission bands are dependent on the sequence of irradiation and cooling. Changes in the relative intensities are caused by the photo- aggregation of the mobile Cu(+) ions to form dimers. These changes are an example of optical memory. The growth of the dimer emission band under ultraviolet excitation is a diffusion controlled process. The quenching of the monomer emission with increasing temperature correlates well with ionic hopping processes. The dynamics of ion motion which produce the green dimer emission band are quantified by a model based upon the thin film solution of Fick's second law.
TL;DR: In this article, the minority carrier lifetime was measured by time-resolved photoluminescence in epitaxial films of GaAs grown by metalorganic chemical vapor deposition.
Abstract: The minority‐carrier lifetime has been measured by time‐resolved photoluminescence in epitaxial films of GaAs grown by metalorganic chemical vapor deposition. The measured lifetimes in thicker devices are 4 to 6 times the theoretical or radiative lifetime. These long lifetimes are the result of photon recycling or self‐generation of the self‐absorbed radiation.
TL;DR: In this article, a grid-inserted quantum well (GI-QW) was constructed on a misoriented GaAs substrate of 2° off from (001) axis by depositing 0.5 ML of AlAs during the growth of a usual QW.
Abstract: We have prepared by molecular beam epitaxy a new type of planar superlattice (PSL), in which an array of periodically spaced AlAs bars of one monolayer (ML) in thickness is inserted in the middle of a GaAs quantum well. This grid‐inserted quantum well (GI–QW) is prepared on a misoriented GaAs substrate of 2° off from (001) axis by depositing 0.5 ML of AlAs during the growth of a usual QW. Photoluminescence excitation spectra are measured at 20 K and have shown a clear dependence on the polarization of the excitation light, reflecting the in‐plane anisotropy of electronic structures. The measured ratio of electron–heavy hole (e–hh) and electron–light hole (e–lh) transition peaks has shown the polarization dependence, which is in good agreement with theory; this demonstrates that 0.5 ML of AlAs atoms deposited on atomic terraces have formed a periodic potential as intended and given rise to the PSL states in this novel structure.
TL;DR: In this paper, high-energy electron diffraction (RHEED) intensity oscillations have been used during molecular beam epitaxy (MBE) to accurately determine threshold layer thicknesses for two-dimensional (2D) growth of InxGa1−xAs/GaAs on GaAs for a wide range of substrate temperatures and indium compositions.
Abstract: Reflection high‐energy electron diffraction (RHEED) intensity oscillations have been used during molecular beam epitaxy (MBE) to accurately determine threshold layer thicknesses for two‐dimensional (2D) growth of InxGa1−xAs on GaAs for a wide range of substrate temperatures and indium compositions. InxGa1−xAs/GaAs single quantum wells were also grown by MBE and studied using low‐temperature photoluminescence (PL) spectroscopy. PL peak energy, intensity, and linewidth measurements provided information on the critical layer thicknesses for the formation of dislocations which, under our experimental conditions, were the same as the threshold layer thicknesses for 2D growth measured from the damping behavior of RHEED intensity oscillations.
TL;DR: In this article, the electron-hole exchange energy, i.e., the energy difference between orthoexciton and paraexciton, is independent of pressure, and the mode Gruneisen parameters for zone-center phonons vary between -3.4 and +1.7.
Abstract: Excitonic transitions and phonon frequencies in ${\mathrm{Cu}}_{2}$O were measured by luminescence and Raman spectroscopy at hydrostatic pressures up to 8.5 GPa and at a temperature of 6 K. The exciton Rydberg energy is found to decrease at a rate of -2.4 meV/GPa. The band gap increases at a rate of 12.5 meV/GPa, which corresponds to a band-gap deformation potential of -1.38 eV. The electron-hole exchange energy, i.e., the energy difference between orthoexciton and paraexciton, is independent of pressure. The mode Gr\"uneisen parameters for the zone-center phonons vary between -3.4 and +1.7. A rigid-ion model for the pressure dependence of k=0 phonon frequencies yields mode Gr\"uneisen parameters which are consistent with the experimental data.
TL;DR: In this article, a dynamic photoluminescence technique has been applied to investigate the active surface species on two different types of Mo/SiO{sub 2} catalysts, which contain lower Mo content (0.01-0.1 wt % Mo) and differ in molybdenum dispersion.
Abstract: A dynamic photoluminescence technique has been applied to investigate the active surface species on two different types of Mo/SiO{sub 2} catalysts, which contain lower Mo content (0.01-0.1 wt % Mo) and differ in molybdenum dispersion. Phosphorescence spectra of the Mo/SiO{sub 2} catalysts, which are attributed to the radiative decay processes from the charge-transfer excited triplet state of tetrahedral dioxo-molybdenum species, appear at {approximately} 440 nm at 298 K and shift to 470 nm at 77 K. The decay curves of the phosphorescence of the anchored and impregnated Mo/SiO{sub 2} catalysts indicate that the anchored catalysts possess only 1 type of Mo emitting site, while the impregnated ones contain at least 2. These results are confirmed by photoluminescence quenching by O{sub 2} or CO, in which the phosphorescence of the anchored catalysts is completely quenched but that of the impregnated samples is only partially quenched. With the anchored catalyst the absolute quenching rate constants of the charge-transfer excited triplet are determined first to be 7.6 {times} 10{sup 7} g of catalyst/mol {times} s for O{sub 2} and 4.2 {times} 10{sup 6} of catalyst mol {times} s for CO, respectively. The phosphorescence spectra of the anchored catalysts obtained at different excitation wavelengthsmore » are found to be the same, being quite different from that of impregnated catalysts, where the phosphorescence spectra change in their position with excitation energies. These results indicate that the dynamic photoluminescence technique is useful for investigation not only of active surface species on metal oxides supported on a carrier at very small concentrations but also of their reactivity in the excited states.« less
TL;DR: Absorption and luminescence spectra for the two superlattices show qualitatively different behavior due to the presence of strain-generated electric fields in the (111) strained-layersuperlattice.
Abstract: We have studied the optical properties of GaInAs/GaAs strained-layer superlattices grown along the (100) and (111) crystallographic axes. Absorption and luminescence spectra for the two superlattices show qualitatively different behavior. These differences are attributed to the presence of strain-generated electric fields in the (111) strained-layer superlattice, which have been predicted theoretically but have not been previously observed experimentally.
TL;DR: In this paper, a GaInAs/InP quantum well was grown by using atmospheric pressure organometallic vapor phase epitaxy with and without interruptions at the interfaces and it was demonstrated that As is effective in substituting for P atoms on the InP surface during AsH3 purge.
Abstract: GaInAs/InP quantum wells were grown by using atmospheric pressure organometallic vapor‐phase epitaxy with and without interruptions at the interfaces. The growth schedule has a major effect on the optical properties of the quantum wells. For approximately 10‐A‐thick wells, the ground‐state energy as determined by 10‐K photoluminescence decreases in the following order: continuous growth, an interruption at the second interface, and interruptions at both interfaces. It is demonstrated that As is effective in substituting for P atoms on the InP surface during AsH3 purge. Varying the AsH3 flow rate during growth of the GaInAs well layer significantly influences the emission energies for samples grown continuously or with an interruption at the second interface. However, the emission energies of quantum wells grown with interruptions at both interfaces are found to be independent of the AsH3 flow rate, indicating insignificant substitution of As for P in the InP barriers. An interfacial layer of InAsxP1−x may...
TL;DR: In this article, the lateral width dependence of the quantum efficiency of the excitonic recombination in etched InGaAs/InP wires (40 nm≤Lx≤5 μm) was investigated.
Abstract: We have investigated the lateral width (Lx) dependence of the quantum efficiency of the excitonic recombination in etched InGaAs/InP wires (40 nm≤Lx≤5 μm). The analysis of data obtained at different temperatures implies that the intensity decay observed for narrow wires is due to the formation of an optically inactive (‘‘dead’’) layer and due to surface recombination.
TL;DR: In this article, a plasmon-pole approximation for dielectric function was used to find the magnetic oscillation of the self-energy of a photo-excited hole in the lowest Landau level.
TL;DR: In this article, solid state investigation of the MSGa2S3 systems (M = Sr, Ba) gives evidence of the existence of the following thiogallates: SrGaS4, Sr2GaS5, BaGaS6, Ba4GaS7, and Ba5(BaS4)2.
TL;DR: In this paper, the temperature dependence of the photoluminescence spectrum of Ga0.5 In 0.5 P/GaAs grown by organometallic vapor phase epitaxy is measured.
Abstract: The temperature dependence of the photoluminescence spectrum of Ga0.5 In0.5 P/GaAs grown by organometallic vapor phase epitaxy is measured. Samples with a highly long‐range ordered structure show anomalous behavior, where peak energy changes with temperature exhibiting Z‐shape dependence. In the range between 100 and 30 K, peak energy decreases monotonously with decreasing temperature, and below 30 K, begins to increase, splitting into two peaks. The most probable cause of this behavior is crystal defects related to the long‐range ordered structure.
TL;DR: A model for the oxygen in ZnSe acting as an acceptor is proposed and the acceptor level and the effective charge of oxygen are estimated to be about 80 meV and -0.9, respectively, using the energy values of the luminescence peaks of bound-exciton and donor-acceptor emission.
Abstract: The optical properties of oxygen-doped ZnSe grown by molecular-beam epitaxy were studied by means of photoluminescence spectroscopy. Oxygen-related peaks were observed at about 4437 and at about 4550 A\r{}, where phonon replicas also appeared. These peaks may be caused by the radiative recombination of excitons bound to neutral oxygen atoms and donor-to-oxygen-acceptor emission, respectively. Observation of donor-acceptor emission in which the acceptor is an isoelectronic acceptor is reported for the first time. Oxygen, which is an isoelectronic impurity in ZnSe, can act as an acceptor in the same way as the generally used dopants such as nitrogen. A model for the oxygen in ZnSe acting as an acceptor is proposed. The acceptor level and the effective charge of oxygen are estimated to be about 80 meV and -0.9, respectively, using the energy values of the luminescence peaks of bound-exciton and donor-acceptor emission.
TL;DR: Luminescence at energy lower than the absorption edge has been investigated in crystals of GaSe, containing different degrees of lattice disorder, as a function of temperature, of photoexcitation intensity, and of excitation energy.
Abstract: Luminescence at energy lower than the absorption edge has been investigated in crystals of GaSe, containing different degrees of lattice disorder, as a function of temperature, of photoexcitation intensity, and of excitation energy. At low excitation intensity, the extrinsic luminescence is composed of broad overlapping bands that present a blue shift when the temperature increases. Their shape and intensity is strongly dependent on the laser excitation frequency and on the degree of lattice disorder. The results are discussed in terms of a model involving the recombination of shallow donors and free electrons with deep acceptors. These two recombination mechanisms and those involving free and bound excitons are found to be competitive. Their relative importance is strongly dependent on the concentration of structural defects, on the temperature, on the excitation intensity, and on the excitation frequency.
TL;DR: In this paper, the authors performed time-resolved photoluminescence on GaAs/AlxGa1−xAs single quantum well structures with an electric field applied perpendicular to the well plane.
Abstract: We have performed time‐resolved photoluminescence on GaAs/AlxGa1−xAs single quantum well structures with an electric field applied perpendicular to the well plane. The quantum wells are coupled to the GaAs continuum through a thin barrier; the escape time of the electrons in the well was measured by time‐resolved photoluminescence. The dependence of the decay time on applied bias was found to agree very well with a simple semiclassical model.
TL;DR: In this article, the behavior of electroluminescence from a sulfur-related impurity complex in a p-n junction formed in epitaxial silicon was characterized and an external quantum efficiency of 0.2-0.5% was obtained.
Abstract: We characterize the behavior of electroluminescence from a sulfur‐related impurity complex in a p‐n junction formed in epitaxial silicon. The spectrum of the electroluminescence matches that of previously reported photoluminescence from sulfur impurities and persists to ∼150 K. In our structure, we find that the electroluminescence exhibits an external quantum efficiency of 0.2–0.5%.
TL;DR: The first observation of strong intersubband (e\-e2) absorption by photogenerated excitons in GaAs/GaAlAs undoped, multi-quantum-well structures is reported.
Abstract: We report the first observation of strong intersubband (e\\-e2) absorption by photogenerated excitons in GaAs/GaAlAs undoped, multi-quantum-well structures. The origin of the transition is verified by polarization measurements, temperature dependence, and comparison with photoluminescence data. Its oscillator strength is found to be approximately 25 times stronger than that measured for bare electrons in modulation-doped quantum wells. We attribute it to an excitonic enhancement.
TL;DR: In this paper, the authors describe a method of confining carriers by deliberately creating large inhomogeneous strain patterns in a quantum well, which modulates the band gap to provide lateral quantum confinement for excitons.
Abstract: We describe a novel method of confining carriers by deliberately creating large inhomogeneous strain patterns in a quantum well The strain modulates the band gap to provide lateral quantum confinement for excitons Here, we generate strain confinement in an InGaAs quantum well by reactive ion beam assisted etching through an overlying compressed pseudomorphic quaternary layer using etch masks patterned by electron beam lithography Photoluminescence spectra of arrays of wires and dots show red‐shifted band gaps in direct evidence of lateral confinement We compare our results to finite element calculations of the inhomogeneous strain in an InP substrate from a compressed overlayer patterned into rectangular wires
TL;DR: In this paper, high-resolution lattice images obtained with transmission electron microscopy of single quantum wells reveal high quality interfaces for both the normal InGaP/GaAs and the inverted GaAs/InGaP interface.
Abstract: High quality quantum wells of GaAs confined by barriers of InGaP have been grown by gas‐source molecular beam epitaxy. High‐resolution lattice images obtained with transmission electron microscopy of single quantum wells reveal high quality interfaces for both the normal InGaP/GaAs and the inverted GaAs/InGaP interface. Multiple‐line low‐temperature photoluminescence emission is observed for the thinnest GaAs quantum well. The range of well thicknesses examined was 0.6–5.2 nm, with the smallest well producing a quantum confinement energy shift of over 410 meV, corresponding to photoluminescence emission at 640 nm (1.94 eV) from GaAs.