Showing papers on "Cathodoluminescence published in 1990"
Book•
01 Jan 1990
TL;DR: The basic concepts of solid state physics have been discussed in detail in this article, where the authors present a review of the main concepts of Solid State Physics and its applications in the literature.
Abstract: 1. Introduction.- 2. Introduction to Basic Concepts of Solid State Physics.- 3. Luminescence Phenomena.- 4. Cathodoluminescence.- 5. Cathodoluminescence Analysis Techniques.- 6. Applications.- 7. Semiconductors.- 8. Phosphors.- 9. Ceramics.- 10. Minerals.- 11. Future Developments.- Books on Solid State Physics.- Books on Optical Properties of Inorganic Solids.- Books Devoted to Scanning Electron Microscopy.- References.
530 citations
TL;DR: It is found that optical excitation of the slow component by a 222-nm laser pulse generates a luminescence band having a peak at 2.1 eV, which is likely that the defect pair and the self-trapped exciton have the same composition and both are generated as the result of the relaxation of excitons.
Abstract: Luminescence and optical absorption induced by an electron pulse and by a subsequent laser pulse have been studied in densified and undensified amorphous Si${\mathrm{O}}_{2}$ at 77 K. We find that the decay of the optical-absorption change induced by an electron pulse consists of two components: one which decays following a power law within 1 ms and the other which decays much more slowly. The fast component exhibits the spectrum of the self-trapped excitons, while the spectrum of the slow component includes the ${E}^{\ensuremath{'}}$ band. The ${E}^{\ensuremath{'}}$ band thus generated is found to decay with a time constant of about 10 h at 77 K and to be annihilated almost completely by warming to room temperature. We also find that optical excitation of the slow component by a 222-nm laser pulse generates a luminescence band having a peak at 2.1 eV, which is identical to the luminescence band due to the self-trapped excitons. It is likely that the defect pair and the self-trapped exciton have the same composition and both are generated as the result of the relaxation of excitons.
130 citations
TL;DR: In this article, the properties of CVD diamond are compared to those of conventional diamond, and to what extent they are unique, and it has been shown that the crystals are relatively free from structural and chemical defects, a conclusion reinforced by the absence of any zero-phonon lines in the absorption spectra of crystals which have been subjected to radiation damage and annealing at 800 °C.
Abstract: Absorption and cathodoluminescence spectra have been recorded for single crystals of diamond and polycrystalline films of diamond, grown by microwave-assisted chemical vapor deposition (CVD) using methane and hydrogen. The investigation has been carried out to see to what extent the properties of CVD diamond are similar to those of conventional diamond, and to what extent they are unique. Studies have been made of the as-grown material, which has not been intentionally doped, and also samples that have been subjected to radiation damage and thermal annealing. The single crystals grown using methane concentrations of 0.5 to 1.0% exhibit bright blue “band A” emission and also intense edge emission, similar to the cathodoluminescence spectra of some natural type IIa diamonds. This implies that the crystals are relatively free from structural and chemical defects, a conclusion which is reinforced by the absence of any zero-phonon lines in the absorption spectra of crystals which have been subjected to radiation damage and annealing at 800 °C. Before radiation damage the spectrum does, however, reveal an absorption which increases progressively to higher energies, and which may be associated with sp2-bonded carbon. The cathodoluminescence spectra after radiation damage indicate that the crystals contain some isolated nitrogen, and the detection of H3 luminescence, following thermal annealing at 800 °C, demonstrates for the first time that these samples contain small concentrations of nitrogen pairs. All of the polycrystalline films, grown using methane concentrations between 0.3 and 1.5%, have an absorption which increases progressively to higher energies, and which again is attributed to sp2-bonded carbon. This absorption is stronger in the films grown using higher methane concentrations. Films grown at a methane concentration of 0.3% also exhibit bright blue cathodoluminescence, although the edge emission is undetectably weak. The use of higher methane concentrations produces films with evidence in the cathodoluminescence spectra of nitrogen + vacancy and nitrogen + interstitial complexes, as well as optical centers unique to CVD diamond. One particular defect produces an emission and absorption line at 1.681 eV. By implanting conventional diamonds with 29Si ions it has been confirmed that this center involves silicon, and it has been shown that the 1.681 eV luminescence is relatively more intense in implanted diamonds which have a high concentration of isolated nitrogen.
123 citations
TL;DR: In this paper, the selective growth of nanometer scale GaAs wire and dot structures using metalorganic vapor phase epitaxy is demonstrated, and a blue shifting of the GaAs peak is observed as the size scale of the wires and dots decreases.
Abstract: The selective growth of nanometer scale GaAs wire and dot structures using metalorganic vapor phase epitaxy is demonstrated. Spectrally resolved cathodoluminescence images as well as spectra from single dots and wires are presented. A blue shifting of the GaAs peak is observed as the size scale of the wires and dots decreases.
106 citations
Journal Article•
105 citations
Book•
16 Nov 1990
TL;DR: In this article, the authors describe the penetration of primary electrons into crystals by incident radiation motion of mobile carriers in crystals energy conversion of electrons penetrated into phosphor crystals optimization of cathodoluminescence phosphors application of phosphors to picture tube rare earth phosphors II-VI compound phosphors characteristic properties of ZnO.
Abstract: Penetration of primary electrons into crystals excitation of activator ions by incident radiation motion of mobile carriers in crystals energy conversion of electrons penetrated into phosphor crystals optimization of cathodoluminescence phosphors application of phosphors to picture tube rare earth phosphors II-VI compound phosphors characteristic properties of ZnO.
101 citations
TL;DR: AlN/GaN layered structures with layer periods between 1.5 and 40 nm have been grown on (0001) oriented sapphire and α(6H)•SiC substrates as mentioned in this paper.
Abstract: AlN/GaN layered structures with layer periods between 1.5 and 40 nm have been grown on (0001) oriented sapphire and α(6H)‐SiC substrates. The growth was performed using a modified gas source molecular‐beam epitaxy (MBE) technique. Standard effusion cells were used as sources of Al and Ga, and a small, MBE compatible, electron cyclotron resonance (ECR) plasma source was used to activate nitrogen gas prior to deposition. Chemical analysis of the layers was conducted using Auger spectrometry. X‐ray diffractometry, transmission electron microscopy (TEM), and high‐resolution electron microscopy (HREM) were employed for the structural and microstructural studies. Coherent interfaces (no relaxation by misfit dislocations) were observed for bilayer periods smaller than 6 nm. By contrast, completely relaxed individual layers of GaN and AlN with respect to each other were present for bilayer periods above 20 nm. Cathodoluminescence showed a shift in the emission peak from 3.42 eV for the sample with individual 10‐n...
98 citations
TL;DR: Oscillatory zoning of Mn in calcite was produced in free-drift solution growth experiments as discussed by the authors, and the fluctuations causing the oscillatory zoning form autonomously in a system far from equilibrium and represent an example of self-organization.
85 citations
TL;DR: In this paper, the authors investigated the emission spectra of undoped and boron-doped diamond formed by plasma assisted chemical vapor deposition and found that cathodoluminescence peaks occurred at 2.8-2.9 eV.
Abstract: Visible luminescence between 2.0–3.5 eV of undoped and boron‐doped diamond formed by plasma‐assisted chemical vapor deposition has been investigated by cathodoluminescence. Electroluminescence from Schottky diode of boron‐doped semiconducting diamond has been observed for the first time and found to be due to the same luminescent center as that of cathodoluminescence. In the particles or films where the content of nitrogen and boron was greatly reduced, the cathodoluminescence peaks occurred at 2.8–2.9 eV. The characteristics of these emission spectra are very similar to those obtained in type‐IIa diamond where dislocations are luminescent. The doping of boron during the deposition form another luminescent center at 2.3–2.4 eV. From the monochromatic cathodoluminescence imaging, the luminescent regions differ in the two peaks. {100} sectors are much more luminescent than {111} sectors at the signal of 2.8 eV. This phenomenon has been discussed based on the difference in defect or impurity concentration of...
84 citations
TL;DR: In this article, the authors examined both undoped and Ge-doped high-purity synthetic quartz over the temperature range 40 to 300 K. The undoped quartz exhibits the well known blue (approximately 470 nm) luminescence attributed to the decay of self-trapped excitons.
Abstract: Cathodoluminescence from undoped and Ge-doped high-purity synthetic quartz is examined over the temperature range 40 to 300 K. The undoped quartz exhibits the well known blue ( approximately 470 nm) luminescence attributed to the decay of self-trapped excitons. Ge-doped quartz shows green ( approximately 570 nm) luminescence at low temperatures; it is proposed that this emission occurs as a result of exciton self-trapping occurring at Ge substitutional sites. Line features which are considered as resulting from molecular oxygen ions are observed in both undoped and doped material. Evidence is presented that emission at 380 nm relates to an impurity incorporated during growth.
70 citations
TL;DR: In this article, the detection limits, emission colours and spectra of calcite containing either Mn, Zn, Sm, Pb, Tb, C, Eu, or Dy have been synthesized and their cathodoluminescence (CL) detection limits and emission colours are described.
TL;DR: In this article, the recombinations of free excitons are located at {100} sectors and the crystal perfection and purity is high in {100] sectors compared with {111} sectors formed in the CVD process.
Abstract: In small particles of chemical vapor deposited (CVD) diamond and polycrystalline thin films composed of the particles, the recombination radiation of free excitons and bound excitons associated with multiple phonons has been observed using cathodoluminescence. The bound excitons are due to neutral acceptors of boron in the diamonds. The cathodoluminescence imaging reveals that the recombinations of free excitons are located at {100} sectors. The crystal perfection and purity is high in {100} sectors compared with {111} sectors formed in the CVD process.
TL;DR: In this paper, the critical layer thickness for dislocation generation and the characteristic thickness for consequent modification of the optical properties of strained quantum wells are shown to be remarkably different, and the dislocations are found to be asymmetrically distributed within the (001) interface plane.
Abstract: The critical layer thickness Lc for dislocation generation and the characteristic thickness for consequent modification of the optical properties of strained quantum wells are shown to be remarkably different. We visualize the misfit dislocations directly using scanning cathodoluminescence and transmission electron microscopy. The dislocations are found to be asymmetrically distributed within the (001) interface plane. The critical thickness for In0.23Ga0.77 As on GaAs is determined to be Lc ≊15 nm in agreement with the theory of Matthews and Blakeslee [J. Cryst. Growth 27, 118 (1974)]. The deterioration of quantum efficiency, a change of recombination dynamics, the increase of spectral broadening and a shift of the band gap occur at much larger thickness than Lc since these quantities are barely affected by low dislocation densities. The relaxation is heterogeneous; strained and fully relaxed domains coexist. Using double crystal x‐ray diffraction we find that partially relaxed layers with thickness larg...
TL;DR: In this article, the authors report cathodoluminescence imaging and transmission electron microscopy (TEM) studies of patterned GaAs/AlAs quantum well (QW) heterostructures grown by molecular beam epitaxy on periodically corrugated substrates.
Abstract: We report cathodoluminescence (CL) imaging and transmission electron microscopy (TEM) studies of patterned GaAs/AlAs quantum well (QW) heterostructures grown by molecular beam epitaxy on periodically corrugated substrates. Faceting and surface diffusion during crystal growth result in significant lateral variations in QW thickness which translate quantum size effects into lateral band‐gap patterning. The CL images directly display lateral periodic modulation in quantum well thickness and indicate the existence of two lateral potential wells formed at the bottom and apex of corrugations. Emission wavelengths are in agreement with TEM data on the patterned structures. Such periodic patterned QW heterostructures should be useful for the realization of arrayed one‐ and zero‐dimensional semiconductor quantum structures, particularly lateral superlattice heterostructures.
TL;DR: In this paper, the Maltese Cross was observed radiating from a growth center that had dominated growth in the direction normal to the (1 mm) surface, covering the entire surface up to its maximum width of 3 mm exposed on the specimen surface remoter from the seed.
TL;DR: The cathodoluminescence spectra of microwave plasma-deposited polycrystalline diamond films have been measured at liquid-nitrogen temperatures over the spectral region of 230-800 nm as discussed by the authors.
Abstract: The cathodoluminescence spectra of microwave plasma‐deposited polycrystalline diamond films have been measured at liquid‐nitrogen temperatures over the spectral region of 230–800 nm. The diamond coatings had been deposited under several different deposition temperatures and reactant compositions. Measurements on natural type‐IIB diamond crystals were made for comparison. The intrinsic exciton emission bands which fall in the UV just below the band edge were observed, as well as several defect and impurity bands which extend throughout the visible part of the spectrum. SEM micrographs and Raman spectra were obtained for the same set of samples used for the cathodoluminescence measurements. It was found that the diamond‐related cathodoluminescence features were most intense in samples whose Raman spectra exhibited the most intense cubic diamond line at 1332 cm−1 and the least intense graphitic band at about 1500 cm−1.
TL;DR: In this article, a single quantum well (SQW) structure growth on GaAs facet wall is achieved by atomic layer epitaxy (ALE) using chloride source gases, such as InCl and GaCl.
Abstract: InGaP/GaAs single quantum well(SQW) structure growth on GaAs facet wall is achieved by atomic layer epitaxy (ALE) using chloride source gases, such as InCl and GaCl. GaAs facets are formed on GaAs(100) surface openings by conventional hydride vapor phase epitaxy, which have {011} sidewalls perpendicular to the surface, {111}B and (100) faces. ALE growth of SQWs onto these faces results in a very smooth and uniform surface, as shown by scanning electron microscopy observation and cathodoluminescence measurements. The self‐limiting mechanism for ALE is also retained in such selective sidewall growth of heterostructures.
TL;DR: In this article, the structural, electrical, and optical properties of ErAs films grown on GaAs by molecular beam epitaxy (MBE) were investigated, and it was shown that strain due to the lattice mismatch between ErAs and GaAs is completely inelastically relieved in the 1500A-thick ErAs layers.
Abstract: A detailed study is presented of the structural, electrical, and optical properties of ErAs films grown on GaAs by molecular beam epitaxy (MBE). ErAs layers 1500A thick were grown successfully over a relatively wide range of substrate temperatures (420-580° C), although overgrowth of GaAs on ErAs was found to be difficult. In-situ reflection highenergy electron diffraction (RHEED), x-ray diffraction, and Rutherford backscattering (RBS) measurements all indicate single crystal growth. Analysis of X-ray rocking curves reveals that, over the range of substrate temperatures studied, strain due to the lattice mismatch between ErAs and GaAs is completely inelastically relieved in the 1500A thick ErAs layers. Variable-temperature Hall measurements reveal metallic behaviour in all samples, with no pronounced dependence on substrate temperature. Spectrally narrow (0.6 meV) intra 4f-shell transitions of Er3+ (4f11), at 1.54 μm, have been observed in ErAs epitaxial layers both in absorption (by Fourier transform infra-red spectroscopy, FTIR) and in emission (by cathodoluminescence). The crystal-field splittings observed in the FTIR spectra are consistent with the cubic(O
h)symmetry expected for the Er lattice site in unstrained ErAs, in good agreement with the x-ray analyses.
TL;DR: In this article, Mn spinels containing between 0 and 8% Mn by weight were prepared by growth from an induction melt, and by Mn + implantation into nonstoichiometric spinel crystals.
TL;DR: In this article, the use of a cathodoluminescence (CL) detector in a scanning electron microscope to form high-resolution CL images of Y2O3, BaCO3, Y2BaCuO5, oxygendepleted YBa2Cu3O7−x(x>0.5), and oxygen-annealed YBa 2Cu3 O7−X(x∼0) is reported.
Abstract: We show that semiconducting and insulating metal‐oxide phases emit substantially greater luminescence when irradiated with 10–30 keV electrons than metallic, candidate high Tc superconducting phases. The use of a cathodoluminescence (CL) detector in a scanning electron microscope to form high‐resolution CL images of Y2O3, BaCO3, Y2BaCuO5, oxygen‐depleted YBa2Cu3O7−x(x>0.5), and oxygen‐annealed YBa2Cu3O7−x(x∼0) is reported. The spatial resolution obtained in CL micrographs of YBa2Cu3O7−x is found to be about 0.1 μm when the electron beam current is 190 nA. The use of CL microscopy in combination with energy‐dispersive x‐ray analysis may be a promising technique for identifying candidate superconducting phases of novel stoichiometry in complex multiphase samples.
TL;DR: In this article, a high energy focused ion beam (Ga+, 150 keV) is used to implant and interdiffuse quantum well structures, and optical properties of wires and boxes created by this technique are evaluated by low temperature cathodoluminescence spectroscopy and imaging.
TL;DR: In this article, the crystal quality and orientation of ZnSe layers were studied by X-ray diffraction and cathodoluminescence at room temperature and 17 K. The influence of the preheating procedure of the GaAs substrate, the substrate temperature and of the Zn-to-Se vapour ratio was investigated.
TL;DR: The cathodoluminescence mode in the scanning electron microscope has been used to image bands of dislocations in zinc oxide as mentioned in this paper, and it has been shown that dislocation lying on pyramidal, {1012}, planes are generated beneath indentations on {0001} surfaces.
Abstract: The cathodoluminescence mode in the scanning electron microscope has been used to image bands of dislocations in zinc oxide. It has been shown that dislocations lying on pyramidal, {1012}, planes are generated beneath indentations on {0001} surfaces. Basal plane dislocations lying parallel to the surface are also observed. Indentations on {1100} prismatic surfaces result in slip on {0001} and {0110} planes.
TL;DR: In this article, the authors report the study of organometallic chemical vapor deposition (OMCVD) on the stepped surfaces obtained by crystal growth on nonplanar vicinal (100)GaAs substrates.
Abstract: We report the study of organometallic chemical vapor deposition (OMCVD) on the stepped surfaces obtained by crystal growth on nonplanar vicinal (100) GaAs substrates. Scanning and transmission electron microscopy investigations were combined to identify two distinct diffusion mechanisms in OMCVD: one mechanism involves the gas phase and allows us to selectively distribute the incoming flux of volatile reactants between two adjacent facets; the other one involves surface diffusion of nonvolatile species over distances in the hundred nm range. Spectrally and spatially resolved cathodoluminescence imaging of the light emissions from a single quantum well structure gives direct evidence that the quantum well thickness variations, which can be controlled over a wide range (up to 1:5) by growth parameters, produce effective band‐gap variations.
TL;DR: In this article, changes in the visible and infrared cathodoluminescence (CL)spectra of YBa2Cu3O7−x were detected during irradiation in the scanning electron microscope.
Abstract: Changes in the visible and infrared cathodoluminescence(CL)spectra of YBa2Cu3O7−x are detected during irradiation in the scanning electron microscope. Results indicate the influence of oxygen content on the appearance of a CL band at 450–600 nm. In irradiated samples an infrared band at 1600–1700 nm has been observed.
TL;DR: In this article, the occurrence of multiple peaks in the 25 K cathodoluminescence spectrum of a sample containing nominally two single quantum wells is caused by terraces differing by one monolayer in thickness, ≊ 2.93 A.
Abstract: High quality, GaInAs, single quantum wells lattice matched to InP barriers, have been grown by metalorganic vapor phase epitaxy at reduced pressures and with the application of short growth interruptions at both heterointerfaces. The occurrence of multiple peaks in the 25 K cathodoluminescence spectrum of a sample containing nominally two single quantum wells is caused by terraces differing by one monolayer in thickness, ≊ 2.93 A, in the same quantum well. For their observation as well defined excitonic emission peaks, the terraces must be larger in lateral extent than the free exciton Bohr diameter, namely, ≊ 350 A. This number sets the lower boundary of the size of the terraces. Cathodoluminescence images were formed for the individual emission peaks and the contrast fluctuations observed with a lateral extent up to ≊ 2 μm give the upper boundary for the extended monolayer‐flat terraces. So far this is the first direct observation of such large growth islands at the heterointerface of the GaInAs/InP system.
TL;DR: In this article, the microcrystalline structure of GaN has been investigated in relation to the micro crystal structure of a Zn-doped GaN layer and an undoped GAN layer grown by metalorganic vapor phase epitaxy (MOVPE) on an α-Al 2 O 3 (0001) (C -face) substrate.
TL;DR: In this article, the authors used a reticon to measure the lateral fluctuations of recombination energy of GaAs quantum well excitons and thus the variation of the GaAs QW thickness L z with monolayer depth resolution.
TL;DR: In this article, the electrical and optical properties of APBs in GaAs epitaxial layers grown on Si substrates were investigated using cathodoluminescence, electron beam induced current, and scanning deep level transient spectroscopy.
Abstract: Electrical and optical properties of antiphase domain boundaries (APBs) in GaAs epitaxial layers grown on Si substrates have been investigated using cathodoluminescence, electron beam induced current, and scanning deep level transient spectroscopy. It was found that APBs reduce near‐band‐gap luminescence and minority‐carrier lifetime. In contrast to recombination at threading dislocations in GaAs films, the nonradiative recombination processes at APBs are not due to deep traps but rather to a continuum of band‐gap states introduced by APBs.