Showing papers on "Photoluminescence published in 1978"
TL;DR: In this paper, the radiative recombination coefficient B was determined from photoluminescence time−decay and external quantum efficiency data taken for LPE GaAs samples (germanium doped or undoped) in the doping range 1.9×1015?p0?1×1019 cm−3 at 300 °K.
Abstract: Minority‐carrier lifetimes, internal quantum efficiencies, and values of the radiative recombination coefficient B are determined from photoluminescence time‐decay and external quantum efficiency data taken for LPE GaAs samples (germanium doped or undoped) in the doping range 1.9×1015?p0 ?1×1019 cm−3 at 300 °K. Measurements are made on isotype double heterostructure samples where the optically exicted GaAs layer is bounded by wider‐band‐gap Ga0.5Al0.5As layers which provide for confinement of minority carriers and also minimize the importance of surface or interfacial recombination on the measured lifetimes. Comparison with time‐decay data for samples without the ternary cladding layers shows the dominant effect of surface and substrate recombination on the decay time if confinement layers are not provided. Luminescence decay times are observed from 1.2 nsec for heavily doped samples up to 1.3 μsec for lightly doped samples. Values of the bulk minority‐carrier lifetimes, radiative lifetimes, and internal ...
288 citations
TL;DR: In this article, the luminescence of single crystalline and powder specimens of β-Ga 2 O 3 has been studied in the temperature range 5 −300°K and the results indicated that the green emission was caused by the recombination of an electron in a V × o or Ga × i center and a hole trapped in a gallium ion vacancy.
282 citations
PARC1
TL;DR: In this paper, the photoluminescence of amorphous silicon was investigated and the luminescence intensity and spectral line shape were shown to be sensitive to many deposition variables, in particular the power coupled into the discharge, the concentration of silane in the gas stream, and the deposition substrate temperature.
Abstract: The photoluminescence of plasma-deposited amorphous silicon is investigated. The luminescence intensity and spectral line shape are shown to be sensitive to many deposition variables, in particular the power coupled into the discharge, the concentration of silane in the gas stream, and the deposition substrate temperature. Maximum intensity is obtained in samples deposited with low power (\ensuremath{\sim}1 W), a silane concentration of \ensuremath{\gtrsim} 10% and a deposition temperature of 200-300\ifmmode^\circ\else\textdegree\fi{}C. ESR studies show that the luminescence intensity is determined by competing nonradiative transitions to localized defect states whose density varies with deposition conditions. The presence of defect states is related to the way hydrogen is incorporated into the samples, but the details of the defect structure are not yet clear. Oxygen impurities are observed to give a broad, weak luminescence peak centered near 1.1 eV. It is suggested that the active oxygen centers are similar to the charged defects postulated for chalcogenide glasses.
253 citations
TL;DR: In this article, photoluminescence time-decay measurements on Ga0.5Al 0.5As/GaAs double heterostructures were made over a wide range of GaAs active layer thickness and doping levels at room temperature.
Abstract: Photoluminescence time‐decay measurements on Ga0.5Al0.5As/GaAs double heterostructures were made over a wide range of GaAs active layer thickness and doping levels at room temperature. Observed decay times τ in variously doped GaAs samples range from 10 to 450 nsec. Effects of self‐absorption of luminescence and doping level are demonstrated for GaAs layer thickness d≳1 μm. For d<1 μm, the observed decay times are nearly independent of doping level and vary almost linearly with d. The data are interpreted in terms of a small interfacial recombination velocity (Si=450±100 cm/sec) at the Ga0.5Al0.5As/GaAs interface. The value of Si determined here is an average over the doping levels examined.
127 citations
TL;DR: In this article, a smooth epitaxial single-crystalline layers of (100) ZnSe on GaAs substrates are grown by a new low-pressure low-temperature organometallic chemical vapor deposition process.
Abstract: Smooth epitaxial single‐crystalline layers of (100) ZnSe on (100) GaAs substrates are grown by a new low‐pressure low‐temperature organometallic chemical vapor deposition process. The strong band‐edge photoluminescence peak and the absence of any substantial luminescence intensity at longer wavelengths indicate an absence of deep trapping centers which is typically not observed in other CVD growth.
125 citations
TL;DR: In this article, it was shown that both the excitation and the luminescence spectra arise from excitons in the surface region of high surface area alkaline earth oxides with a much lower frequency than that expected from the band gaps of the bulk oxides.
Abstract: Photoluminescence has been observed from high surface area alkaline earth oxides with exciting light of a much lower frequency than that expected from the band gaps of the bulk oxides. This luminescence can be quenched by oxygen and hydrogen and the quenching is reversible under some conditions. It seems probable that both the excitation and the luminescence spectra observed arise from excitons in the surface region. The different behaviour towards oxygen and hydrogen has been used to develop a model in which the excitation site, where absorption of light occurs, is thought to be associated with anions on the surface in states of unusually low coordination such as might be found at step, edge or corner sites on the surface. The luminescence is thought to be associated with a cation on the surface in a similar state of coordination.
116 citations
TL;DR: In this article, optically detected ESR to the yellow photoluminescence of Li doped ZnO gives ESR spectra for shallow donor - lithium acceptor pairs, showing that at least a fraction of the yellow emission is donor-acceptor (D-A) luminescence.
101 citations
TL;DR: In this article, the epitaxial layers of GaAs were grown on GaAs(100) at substrate temperatures ranging from 400° to 600°C by molecular beam epitaxy.
100 citations
TL;DR: In this article, the elastic and misfit strain in vapor-grown InGaP/GaAs crystals was determined by measuring the lattice parameter of the inGaP before and after removal of the GaAs substrate.
Abstract: The elastic and misfit strain in vapor‐grown InGaP/GaAs crystals was determined by measuring the lattice parameter of the InGaP before and after removal of the GaAs substrate. The energy‐band‐gap shift as a function of strain was measured in a similar manner using photoluminescence. Up to 70% of the misfit strain was found to be accommodated elastically. The critical resolved shear stress for dislocation motion was found to be ∼2×109 dyn/cm2. The rather low band‐gap shift with applied stress of ∼3×10−9 meV/dyn cm−2 was attributed to the Poisson effect. Photoluminescence was found to be a very accurate means to measure composition (and therefore lattice parameter), and empirical expressions were determined for the variation of photoluminescence wavelength with composition, lattice parameter, and energy band gap.
88 citations
TL;DR: In this paper, the authors reported the observation of visible photoluminescence in the amorphous SixC1−x(H) alloy system, which consists of two bands one of which shifts linearly with x. For x = 0.4 the principle luminescence maximum lies at 2.1 eV.
Abstract: We report the observation of visible photoluminescence in the amorphous SixC1−x(H) alloy system. The spectrum consists of two bands one of which shifts linearly with x. For x=0.4 the principle luminescence maximum lies at 2.1 eV.
78 citations
IBM1
TL;DR: In this article, the pressure dependence of the photoluminescence intensity and the pressure coefficient of the X 6 conduction band minimum in GaAs has been determined, based on which the pressure of the zone edge phonon energies was also reported.
PARC1
TL;DR: The photoluminescence decay of glow-discharge-deposited amorphous silicon is reported in this article, where the low temperature radiative lifetime of the broad luminescence band near 1·3 eV is found to be about 30 μs.
Abstract: The photoluminescence decay of glow-discharge-deposited amorphous silicon is reported. The low temperature radiative lifetime of the broad luminescence band near 1·3 eV is found to be about 30 μs, and is independent of luminescence energy. The long lifetime is possibly due to weak electron-hole overlap. A competing non-radiative process dominates in weakly luminescent doped and undoped samples, and is thought to be due to tunnelling of an exciton to a nearby defect.
TL;DR: In this paper, the authors measured the optical absorption and photoluminescence emission spectra of terbium doped sodium and lithium aluminium silicate glasses and concluded that energy transfer from 5 D 3 to 5 D 4 levels begins at Tb 3+ ion separations of 20 A, and that the process is multipolar.
TL;DR: In this article, the decay time of photoluminescence from the N3 centre of a natural diamond has been investigated and it was found to be 41 ± 1 ns at low temperature, decreasing with increasing concentrations of pairs of substitutional nitrogen atoms in the diamonds.
Abstract: Measurements are reported of the decay time of photoluminescence from the N3 centre: an impurity centre commonly found in natural diamond. The intrinsic decay time at low temperature is found to be 41 ± 1 ns. The decay time is specimen dependent, decreasing with increasing concentrations of pairs of substitutional nitrogen atoms in the diamonds. The data are consistent with an electric dipole, electric-quadrupole coupling of the N3 centres to the nitrogen pairs. In addition, the decay time is reduced by raising the specimen temperature, especially above 450 K. These results are consistent with internal conversion occurring into another excited electronic state of the N3 centre. The properties required for this state agree with deductions from other optical and electron paramagnetic resonance (e. p. r.) data. The radiative lifetime of the N3 luminescence transition is estimated at 150 ns, in agreement with previous luminescence efficiency measurements.
TL;DR: Effects of ion etching on the optical properties and lattice disorder of GaAs were studied by means of photoluminescence, He backscattering, and enhanced chemical etching to show the existence of an amorphous layer, the thickness of which is 20% larger than the value estimated by LSS theory.
Abstract: Effects of ion etching on the optical properties and lattice disorder of GaAs were studied by means of photoluminescence, He backscattering, and enhanced chemical etching. The photoluminescence intensity excited by a He–Cd laser (3250 A), which penetrates a distance of approximately 150 A into GaAs, is decreased to less than 20% of the initial value after ion etching by 100-eV Ar and recovered almost completely by 450° C annealing. Helium backscattering and electron diffraction pattern indicate the existence of an amorphous layer, the thickness of which is 20% larger than the value estimated by LSS theory. Photoluminescence measurement shows that beyond this amorphous region there are distributed a lot of nonradiative recombination centers as well as radiative recombination centers which diffuse into the bulk. The depth of this distribution is larger than that of the amorphous region by 1 order of magnitude.
TL;DR: In this paper, the decay times of Ga0.5Al0.1.5As−GaAs double heterostructures over a wide range of GaAs active layer thickness and doping levels were investigated.
Abstract: Photoluminescence time‐decay measurements (300 K) are reported for Ga0.5Al0.5As–GaAs double heterostructures over a wide range of GaAs active layer thickness and doping levels. Decay times range from 10 to 650 ns in variously doped GaAs samples. Effects of self‐absorption of luminescence and doping level on the decay times are observed for GaAs layer thickness d≳1 μm. For sufficiently thin GaAs layers, interfacial recombination is believed to determine the decay time. The interfacial recombination velocity is observed to vary from Si=300 cm s−1 for p=5×1015 cm−3 heterostructures to Si=500 cm s−1 for p=1.7×1017 cm−3.
TL;DR: The photoluminescence spectra of CuGaSe2 were measured on melt-solidified crystals, iodine vapour transported as-grown crystals and annealed crystals in various conditions.
Abstract: The photoluminescence spectra of CuGaSe2 are measured on melt-solidified crystals, iodine vapour transported as-grown crystals and annealed crystals in various conditions. From the change in the spectra among them and the influence of annealing on luminescence, it is concluded that the iodine impurity acts as a deep donor which has been unintentionally incorporated into crystals during growth, and that the selenium vacancy acts as a shallow donor. The latter defect can be filled back by annealing in selenium vapour at 600°C. All photoluminescence bands observed in the iodine vapour transported crystals are explained in trems of these two donors (0.38 eV and 80 meV) and one acceptor (40 meV), which is probably due to the copper vacancy.
TL;DR: In this article, it was shown that luminescence centres in chalcogenide glasses are not charged as is widely believed and that electron-hole pairs at such centres are tightly bound.
Abstract: New experimental results are reported which suggest that luminescence centres in chalcogenide glasses are not charged as is widely believed. Measurements of the photoluminescenee excitation quantum efficiency and the absence of any effect on the luminescence of intense magnetic or electric fields strongly suggest that the centres are neutral and that electron-hole pairs at such centres are tightly bound. A number of other recent experiments are reviewed which offer additional evidence for a dipole-centre model of luminescence. In this model, dipole centres (perhaps intimate valence-alternation centres) are excited by absorbed photons, some luminescence is emitted by the excited state in ∼ 10−8 s before it decays into a meta-stable state which lives for ∼ 10−4 s. During the latter time diffusion and energy transfer take place. The time and temperature dependence of photoluminescence fatigue is also reported. Since the temperature dependence of fatigue is so different from that of the luminescence,...
TL;DR: In this article, photoluminescence measurements on Si-doped GaAs single crystals heat treated in vacuum at 400≲T≲800 C reveal emission peaks at 1.363, 1.409, and 1.487 eV, which correspond to three acceptor levels introduced through activation of vacancies and the site transfer of Si atoms during the annealing process.
Abstract: Photoluminescence measurements on Si‐doped GaAs single crystals heat treated in vacuum at 400≲T≲800 °C reveal emission peaks at 1.363, 1.409, and 1.487 eV, which correspond to three acceptor levels introduced through the activation of vacancies and the site transfer of Si atoms during the annealing process.
TL;DR: The photoluminescence spectra of CuGaSe2 have been investigated at 76 K in the range 0.65 3 4 m grating monochromator as mentioned in this paper, and the luminescence observed consisted of a rather sharp structure near the energy gap, plus two broad peaks at considerably smaller energies.
Abstract: The photoluminescence spectra of CuGaSe2 have been investigated at 76 K in the range 0.65 3 4 m grating monochromator. The luminescence observed consisted of a rather sharp structure near the energy gap, plus two broad peaks at considerably smaller energies. The broad peaks, centered around 1.52 and 1.30 eV respectively, are attributed to transitions involving deep localized states. The sharper structure near the energy gap is resolved into two peaks, one at 1.72 eV and another at 1.68 eV. This structure is explained by radiative recombination of free excitons (peak at 1.72 eV), and by recombination of free electrons with bound holes (peak at 1.68 eV). A thermal treatment done on the CuGaSe2 crystals changed both their electrical properties and their luminescence spectra. These changes produced by sample treatment, plus measurements of the excitation power dependence and the polarization of the luminescent radiation, are in agreement with the interpretation presented.
TL;DR: In this article, it was shown that the fundamental oscillating quantity in GaAs at low temperatures is the electron effective temperature, which in turn influences other quantities such as electron densities, electron and exciton effective temperatures are shown to oscillate as a function of exciting energy.
Abstract: The excitation spectroscopy of photoluminescence lines in semiconductors, i.e. the study of the variation of intensity and lineshape of the lines with exciting photon energy, permits to follow in a detailed manner the energy relaxation path of hot photocreated electrons. Many quantities such as electron and exciton densities, electron and exciton effective temperatures are shown to oscillate as a function of exciting energy. We show that the fundamental oscillating quantity in GaAs at low temperatures is the electron effective temperature, which in turn influences other quantities. The possibility to measure at once the electron density and the electronic temperature permits to explain oscillatory photoconductivity.
TL;DR: In this article, the results of the recent models of charged defects in chalcogenides were discussed in terms of the effect of the charged defects on the photoluminescence and photoinduced ESR.
Abstract: Thallium in $a$-${\mathrm{As}}_{2}$${\mathrm{Se}}_{3}$ reduces transient hole transport but has no effect upon the photoluminescence and photoinduced ESR. The results are discussed in terms of the recent models of charged defects in chalcogenides.
TL;DR: In this article, the reversible change in photoluminescence intensity with change in gaseous ambients (N2, Ar, H2, O2, H 2O, and vacuum) from a GaAs cleaved (110) surface when exposed to oxygen were observed at room temperature.
Abstract: The reversible change in photoluminescence intensity with change in gaseous ambients (N2, Ar, H2, O2, H2O, and vacuum) from a InP cleaved (110) surface and the irreversible change in photoluminescence from a GaAs cleaved (110) surface when exposed to oxygen were observed at room temperature. These phenomena imply that adsorbed N2, H2, Ar, H2O, and O2 gases can be exchanged reversibly on the InP surface, and the surface recombination velocity changes reversibly with the adsorbed gas species. On the other hand, oxidation proceeds rapidly and irreversibly on GaAs cleaved surfaces.
TL;DR: In this article, the photoluminescence spectra of quantum-well laser diodes were shown to extend well into the region of the recently determined L band minima of GaAs.
Abstract: Data are presented showing that quantum‐well (Lz∼200 A) AlxGa1−xAs‐GaAs‐AlxGa1−xAs heterostructures, grown by metalorganic chemical vapor deposition, can be operated as lasers on confined‐particle transitions over an unusually large range (Δλ≳1000 A). The bandfilling properties of these quantum‐well heterostructures, which can easily be excited to carrier densities as high as n≳1019/cm3, are described. Quantum‐well laser diodes (x∼0.5) are described that operate (300 K) from the Γ band edge to wavelengths as short as 7700 A (ΔE∼185 meV). Narrow photopumped samples (15–30 μm) are shown to operate (77 K) as lasers on clearly defined confined‐particle transitions from the band edge to 6980 A (ΔE∼270 meV). On samples from another wafer, laser operation has been observed to 6885 A (ΔE≡hν−Eg=293 meV). The photoluminescence spectra of these heterostructures extend well into the region of the recently determined L band minima of GaAs.
Patent•
05 Jan 1978
TL;DR: In this paper, a method and apparatus for background correction in photoluminescent analysis of a selected photoluminous target substance with a relatively narrow emission spectrum in the presence of ambient substances with a combined photolumninescent spectrum which is relatively broad is presented.
Abstract: A method and apparatus for background correction in photoluminescent analysis of a selected photoluminescent target substance with a relatively narrow emission spectrum in the presence of ambient substances with a combined photoluminescent spectrum which is relatively broad. The photoluminescence of the target substance is sampled and measured in a narrow wavelength band corresponding to the principal emission spectrum of the target. A second sample of photoluminescence is measured in one or more wavelength bands adjacent to the first wavelength band, but excluding substantially all of the photoluminescence of the target substance, and transmitting only ambient photoluminescence. The second measurement is converted into an amount which would occur if ambient photoluminescence had been sampled in the first wavelength band and then the converted amount is subtracted from the first measured amount, thereby correcting the first measured amount for photoluminescence derived from ambient substances.
TL;DR: In this paper, the photoluminescence from polymer films of polyethylene terephthalate (PET), polybutylene-terephthalates (PBT), polyparaxylylene (Parylene N) and polymonochloroparaxylene (Polymorphic Parylene C) was investigated.
Abstract: Photoluminescence from polymer films of polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyparaxylylene (Parylene N) and polymonochloroparaxylene (Parylene C) was investigated. Room temperature fluorescence spectra of these polymers were considered to be composed of a monomer emission and an excimer emission. Luminescence at 88 K showed structured phosphorescence in addition to the fluorescence emission observed at room temperature. The chemical substitution of a hydrogen atom in benzene rings by a chlorine atom or carbonyl groups mainly affected the monomer fluorescence emission.
TL;DR: In this paper, a cw dye laser, tunable in the region 570-620 nm, has been used to excite photoluminescence in the A2Π-X2Σ+ system of the YO molecule.
TL;DR: In this paper, the physical, electrical, and optical properties of this mixed crystal were studied and the electron mobility was found to vary from 5240 to 8500 cm2 V−1 sec−1 and electron concentration from at 300° K.
Abstract: Undoped crystal films with very homogeneous composition were grown on substrates by liquid phase epitaxy. Study was made on physical, electrical, and optical properties of this mixed crystal. The growth temperature was varied between 550° and 750°C. All the crystals were n‐type. The electron mobility was found to vary from 5240 to 8500 cm2 V−1 sec−1 and the electron concentration from at 300° K. Etch pit density and half‐width of photoluminescence spectra decreased with increasing growth temperature. High quality crystals were grown at around 700°C.
TL;DR: In this paper, a series of doping experiments have determined the effective segregation coefficient to be 1.6 × 10−3 for Fe in polycrystalline InP, and semi-insulating InP crystals with resistivity > 107 ohm-cm have been grown consistently from melts doped with 150 ppm Fe.
Abstract: Bulk polycrystalline InP is synthesized from the elements via a gradient freeze process. Hall data for a typical boule are Nd-Na= 4.7 × 1015/cm3 and Μ77 = 28,000 cm2/V-sec. Photoluminescence data indicate that zinc is present as an acceptor impurity in the polycrystalline InP and in nominally undoped LEC single crystals grown using the synthesized InP as charge material. A series of doping experiments have determined the effective segregation coefficient to be 1.6 × 10−3 for Fe in InP. Semi-insulating InP crystals with resistivity > 107 ohm—cm have been grown consistently from melts doped with 150 ppm Fe.