Showing papers on "Cathodoluminescence published in 1973"

A study of SiO layers on Si using cathodoluminescence spectra

Abstract: Cathodoluminescence spectra were used to study centers in thin layers of thermally grown SiO2 on Si. The purpose was to learn more about the centers responsible for the radiation induced space-charge build-up observed in oxide-passivated, planar devices. The spectra were observed to contain three broad peaks; peak A at ∼2900A, peak B at ∼ 3700A and peak C at ∼ 4500A. These spectra were not affected by the conductivity-type, resistivity or crystalline orientation of the silicon, and were little affected by the oxide thickness or growth temperature. Ionizing radiation, destroyed the B peak, greatly enhanced the C peak but had little effect on the A peak. Wet-oxygen-grown oxides were less affected by ionizing radiation than were dry-oxygen-grown oxides. Baking wet-oxygen-grown oxides in dry nitrogen at ∼ 1100°C enhanced the B and C peaks. An etch-back experiment was used to determine the distribution of the three luminescence centers. The A center was distributed approximately uniformly throughout the bulk of the oxide. The B center was concentrated near the outer surface of the oxide layer and was undetectable close to the Si/SiO2 interface. The C center was located principally within < 200 A of the Si/SiO2 interface. The A center is believed due to the presence of Na. The B center is associated with the presence of H and may be due to interstitial H. The C center is believed to be the center responsible for the radiation induced space-charge buildup near the Si/SiO2 interface and to be due to trivalent Si. The C center is apparently the same center which produces the C absorption band (2150A) in fused silica.

Depth‐resolved cathodoluminescence in undamaged and ion‐implanted GaAs, ZnS, and CdS

Abstract: Here we report a variety of results obtained by using sequences of luminescence spectra excited by 1–20‐keV electron irradiation to carry out in situ studies of depth‐dependent optical activity in luminescent crystals. Data are shown for various samples subjected to localized damage from ion implantation: GaAs implanted with Cu+, ZnS implanted with Ar+ and Cu+, and CdS implanted with Ar+ and H+. Semiquantitative interpretation of the results shows that the depth‐resolved cathodoluminescence measurements can have unique value in characterizing the effects of ion‐implantation lattice damage. In this case cathodoluminescence can be excited from depths ranging from much shallower to much deeper than typical implant depths. In addition, the use of depth‐resolved measurements on nominally undamaged ZnS crystals reveals the presence of weak near‐surface luminescence bands despite careful surface preparation. This result makes it clear that luminescent center profiling by layer removal methods can lead to erroneo...

Spontaneous and stimulated recombination in p + -n-n + (AlGa)As-GaAs heterojunction laser diodes

Abstract: A detailed study has been made of the lasing properties of p+-n-n+double heterojunction lasers where the n-type active region was lightly doped n type ( \sim 2 \times 10^{16} cm-3) and only weakly compensated. The structure of the diodes allowed a study of the spontaneous emission (below and above lasing threshold) through the nonabsorbing higher band-gap (AlGa)As surface of the diode. Only a single major spontaneous band is seen which peaks near the band-gap energy of the n-type active region. (However, when viewed only through the diode edge, a second spurious lower energy "ghost peak" is seen due to selective internal absorption of the spontaneous radiation in the GaAs substrate.) With increasing current density, the spontaneous emission band broadens with a slight upward shift in its peak energy. The lasing peak eventually emerges from the low-energy tail of the band at an energy where relatively little spontaneous radiation is observed at low current densities and where the absorption coefficient is relatively small. Observations made by cathodoluminescence of GaAs with similar doping shows an analogous behavior, with the energy separation between the spontaneous and lasing peaks increasing with increasing temperature between 77 and 300 K. The observed behavior is consistent with the hypothesis that the lasing transitions involve conduction and valence band tail states due to the screening of the crystal field (and carrier interaction) by the high density of injected carriers in the active region of the laser.

Cathode‐ray‐excited luminescence and thermoluminescence of a synthetic calcite monocrystal

Abstract: Artifical calcite single crystals are grown by the hydrothermal method. Their luminescence under cathode ray bombardment is studied. Cathodo-thermoluminescence gives results extending those known for natural calcite. The cathodoluminescence displays, besides the orange-red emission attributed to manganese, an emission around 373 nm. Near liquid helium temperature, the emission of manganese disappears. Des monocristaux de calcite synthetique, obtenus par voie hydrothermale, sont l'objet de mesures de luminescence sous bombardement electronique. En cathodo-thermolumines cence les resultats de la calcite naturelle sont retrouves et etendus. En cathodoluminescence on observe, en plus de l'emission rouge orange due au manganese, une emission autour de 373nm. A une temperature proche de l'helium liquide l'emission du manganese a disparu.

Optical properties of photochromatic sulfur-doped chlorosodalite

Abstract: Synthetic.photochromic sulfo-chlorosodalite, 6(NaAlSiO4) ·2 NaCl(S), has been thoroughly investigated by measurements of optical absorption, photo-luminescence and cathodoluminescence. Depending on the sulfur ion form and concentration, the doped sodalite exhibits either sensitive tene-brescence or photoluminescence with long wavelength UV excitation. The photo-induced color absorption peaks at 5260A at 300°K with absorption coefficient, Δαmax >200 cm−1 . This is by far the highest photo-induced absorption observed for synthetic chlorosodalite. At 80°K, the peak position of the absorption does not show significant shift within instrumental accuracy. In photoluminescence, the emission spectra as well as the excitation spectra are studied at both 300 and 78°K. Four characteristic spectral bands (IR, blue, red, and a band with oscillation in wavelength) are observed. The oscillatory S2 - ion emission band starting about 2.35 eV and extending to lower energy and the IR band peaked at 1.4 eV are most efficiently excited by 3660A (3.4 eV), whereas the blue luminescence peaked at 2.7 eV has an excitation threshold of 3.9 eV. The red band is often masked by the oscillatory band and can be observed by higher energy excitation. The red and blue bands are also observable in the cathodoluminescence measurements of the sulfur-doped samples but not the undoped samples. Correlating the absorption, luminescence, and excitation spectral results, a quantitative model is derived to interpret the nature and the role of sulfur ions in the photochromic chlorosodalite material.

Cathodoluminescence study of plastically deformed GaAs

Abstract: Infrared cathodoluminescence (IR–CL) micrographs were taken of surfaces perpendicular (11¯2) and parallel (021) to the bend axis [11¯2] of GaAs single crystals bent at 700 °C in four‐point bending to introduce α‐Ga and β‐As dislocations. At the bend center, light and dark checkered patterns associated with dislocations could be observed only in the IR–CL micrographs but not by optical, infrared, or secondary electron emission microscopy. Dislocation densities to ρ ≈ 5 × 106 cm−2 could be determined nondestructively to within 20% of the theoretical values. No significant changes related to the type of dislocation or dislocation density were observed either in the peak half‐width or peak position at E = 1.411 eV. However, decreases of 40–70% in the relative IR–CL intensity were observed in the bent samples with predominantly α or β dislocations.

Green electroluminescence in GaP diodes and its correlation with cathodoluminescence measurements

Abstract: The results of a programme of research on green-emitting epitaxial diodes are reported. Diode quantum efficiencies of 0?07% DC and 0?40% pulsed have been obtained from an optimized structure. Room-temperature cathodoluminescence measurements on the bulk regions of device structures are correlated with diode performance. Major correlations are found in luminescence efficiency, light output characteristics and spectral distribution; the last is analysed in some detail to elucidate the room-temperature luminescence mechanisms. These results, coupled with the results of attempts to change the minority carrier injection ratio in the structure and the analysis of diode characteristics, have enabled the operation of our diodes to be understood in terms of abrupt junction theory.

Scanning electron microscope observations of herbicide dispersal using cathodoluminescence as the detection mode.

Abstract: When high energy electrons strike a specimen in an electron microscope a number of phenomena occur. Some electrons are reflected with little or no energy loss. Others actually penetrate the specimen to some degree and excite molecules within a volume of the solid. Some molecules divest themselves of their surplus energy by allowing excited electrons to escape from their orbitals. If these electrons are able to escape from the specimen, they are known as secondary electrons. If the excited electrons do not leave the molecule but instead fall back to their ground state, they must transfer their surplus energy to other molecules or emit it as discrete packages of energy. The emission can be heat, infrared to visible light, or x-rays (for further details of these processes see 1, 4, 7, 8). We will confine ourselves to a consideration of the infrared to visible light production and reflected electron phenomena in this communication. Researchers working with herbicides frequently have a need to know the spatial location of an herbicide in or upon a plant. A common method for obtaining such information is that of radioautography (9). Radioautography, while certainly adequate for many studies, often requires weeks of exposure time to produce a sufficiently intense film image and also involves the expense of radioactively labeled compounds. A number of compounds will fluoresce3 under electron bombardment (3). We have used a scanning electron microscope equipped to detect this fluorescence (cathodoluminescence) and wish to report a new, rapid method for spatially localizing herbicides on leaf surfaces.

Metal-insulator-semiconductor electroluminescent diodes in single-crystal zinc oxide

Abstract: Blue?violet electroluminescence has been observed in forward-biased zinc-oxide diodes of the metal?insulator?semiconductor variety. The power efficiency was about 0.005% at 300 K. The emission spectra can be correlated with those obtained from cathodoluminescence measurements.

Time resolved spectroscopy involving multiply ionizable donor-acceptor states

Abstract: The decay of cathodoluminescence produced by pulsed excitation has been studied for as-grown and phosphor doped zinc telluride. Analysis of the shift of the peak emission energy positions during the decay has been used to determine acceptor concentrations, transition probabilities, fraction of pairs excited and donor depth. Further substantiative evidence for the assignments by Bryant and Baker (1972) of the four emission bands to transitions into the first and second charge states of a double acceptor centre involving a zinc vacancy has been obtained.

Scanning electron microscope studies of electroluminescent diodes of GaAs and GaP

Abstract: GaAs laser diodes and GaP lamp diodes were examined by scanning electron microscopy using the emissive, conductive, and cathodoluminescence modes of operation. Observations of non-uniform doping and gross malformation of p-n junctions were made in both types of device. The dependence of the contrast due to segregation and impurity growth striations on the impurity concentration and the type of photomultiplier used isoutlined. The cathodoluminescence micrographs of GaAs lasers exhibited the same contrast as the charge collection, barrier electron voltaic effect micrographs in regions in the n-type material well away from the junction. This is evidence that both types of signal in these regions arise from the infrared radiation generated by electron beam bombardment. GaAs-Laserdioden und GaP-Lampendioden wurden mit Scanning-Elektronenmikroskopie untersucht, wobei Emission, Leitfahigkeit und Kathodolumineszenz benutzt wurde. Beobachtungen der nichtgleichformigen Dotierung und grober Fehlbildung des p-n-Ubergangs wurden an beiden Typen der Bauelemente durchgefuhrt. Die Abhangigkeit des Kontrasts infolge von Segregation und Storstellenwachstumsstreifen von der Storstellen-konzentration und vom benutzten Photomultipliertyp wird dargestellt. Die Kathodolumineszenzmikrographien der GaAs-Laser zeigten denselben Kontrast wie die Mikrographien des mit Ladungsansammlung verbundenen Barrierenphotospannungseffekts in n-leitenden Bereichen des Materials weit entfernt vom Ubergang. Dies gibt einen Hinweis darauf, das beide Signalartenin diesen Bereichen von der Infrarotstrahlung heruhrt, die durch dieElektronenbestrahlung erzeugt wird.

Method and apparatus for electron beam alignment with a semiconductor member

Abstract: A method and apparatus are provided for alignment of an electron beam with precisely located areas of a major surface of a semiconductor member. The semiconductor member generates cathodoluminecence of intensity corresponding to the thickness thereof. The semiconductor member has formed adjacent a major surface at least one and preferably at least two widely spaced detector marks of predetermined shape capable of providing a differential in cathodoluminescence generated by the member corresponding to the area of the mark irradiated by an electron beam. To align, an electron beam to be aligned has alignment beam portions corresponding to at least one detector mark and of predetermined cross-sectional shapes. The alignment beam portions are projected onto the major surface of the semiconductor member in the vicinity of the corresponding detector marks. And the cathodoluminescence generated by the member at least in the vicinity of the member is detected by detecting means. The electron beam is moved relative to the semiconductor member while continuing said detection until the detected cathodoluminescence indicates optimum alignment of each alignment portion thereof with a corresponding detector mark. Preferably, said alignment method is used in producing a very accurate component pattern in electroresist layer on the major surface of the semiconductor member with either a scanning electron beam or a patterned electron beam generated by a photocathode source.

The parameters of ytterbium implantation in CdS, ZnS and ZnSe

Abstract: The intensity of the characteristic Yb3+ cathodoluminescence emission spectrum has been used to monitor the implantation of ytterbium in cadmium supplied, zinc sulphide and zinc selenide. The effects on the implantation of varying ion fluency, ion flux, implant temperature and anneal temperature have been studied and found to be important. Optimum values of these parameters for ytterbium implantation have been determined. It has been shown that implantation at liquid helium temperatures rather than at higher temperatures can lead to greater structure in the emission spectrum of the implanted ion, and sometimes to greater intensity also. Emission intensity did not decrease monotonically with ion flux but reached a peak at an ion flux of 0μ2 μA cm−2 for annealed cadmium sulphide samples.

Interpretation of asymmetric band shapes in terms of bound exciton complexes

Abstract: The cathodoluminescence edge emission of zinc telluride has been found to contain a most unusual broad, asymmetric emission band which, at 77 K, occurs at 526.2 nm (2.356 eV). The observed properties of this band as a function of temperature and excitation intensity cannot be explained in terms of conventional luminescence models. It is shown that a model for this centre based on the binding of an exciton to a dipolar field resulting from an ionized donor-acceptor pair can account for the anomalous behaviour of the emission, under the assumption that appreciable lattice relaxation occurs in the vicinity of the bound exciton complex.

Method and apparatus for electron beam alignment with a member by detecting cathodoluminescence from oxide layers

Abstract: A method and apparatus are provided for alignment of an electron beam with precisely located areas of a major surface of a semiconductor member. At least one and preferably two spaced apart detector marks of predetermined shape formed by cathodoluminescent oxide layers are positioned adjacent the major surface. Each detector mark provides a differential in cathodoluminescence projected by the oxide layer corresponding to the area of the mark irradiated by an electron beam. To align, an electron beam to be aligned has at least one alignment beam portion corresponding to at least one detector mark and of predetermined cross-sectional shape. The alignment beam portions are projected onto the major surface of the member in the vicinity of the corresponding detector marks. And the cathodoluminescence generated by the oxide layers in at least the vicinity of the detector mark is detected by detecting means. The electron beam is moved relative to the member while continuing said detection until the detected cathodoluminescence indicates optimum alignment of each alignment beam portion thereof with a corresponding detector mark. Preferably, said alignment method is used in producing a very accurate component pattern in electroresist layer on the major surface of the member with either a scanning electron beam or a patterned electron beam generated by a photocathode source.

The growth and properties of luminescent films on silicon

Abstract: Luminescent films on silicon might be used to make monolithic display devices if they could be prepared with suitable properties. Thin films of zinc orthosilicate have been grown on single crystal silicon by the chemical reaction between a thermal oxide and a thin layer of zinc fluoride. Such films, activated with manganese, show the bright green cathodoluminescence of the phosphor willemite. The technique used is not critical and the films are uniform, stable and strongly adherent to the silicon. The electrical properties of the films have been investigated and compared with those of adjacent MOS structures by measuring capacitance-voltage characteristics. These show the presence of mobile positive ions in willemite. The current-voltage characteristics are very variable but some samples show a rapid increase in current with positive voltage applied to the metal accompanied by extremely weak green electroluminescence. The light output would need to be greatly increased before the electroluminescence of these films could be used for display devices.

A rapid scanning spectromerer and time averaging method for cathodoluminescence

Abstract: A description is given of a cathodoluminescence instrument and contol system. Study of signal to noise ratio. Improvement due to filter and use of a time averaging method. Luminescence spectra of CdS and HgS, illustrating the capabilities of the instument.

Photoluminescence, Optical Absorption, and Cathodoluminescence in Ion Implanted CdS

Abstract: Photoluminescence and optical absorption have been measured at 90 K in undoped CdS before and after ion bombardment at 90 K and as a function of isochronal annealing to 350 K. Implantation with Ar+, Cu+, Cl+, He+, or H+ ions at energies sufficient to penetrate the depth of most of the U.V. excitation severely quenches all the luminescence and introduces continuous absorption beyond the absorption edge. These effects are observed for fluences of ~ 2 × 1014 cm-2 for H+ and ~ 5 × 1011 cm-2 for the heavier ions. However, upon annealing to 350 K the ion-induced absorption disappears and the green edge emission at 5200 A, which is seen initially in almost all samples, partially recovers. A more striking change is the growth of a broad red band at 7200 A to intensities much greater than observed prior to implant of the above ions. The red emission center is believed to be a relatively simple native defect center which, upon annealing, evolves from the more complex damage introduced initially by the implantation.

Luminescence Study of the Electronic Band Structure of Inl-xGaxAsl-yPy

Abstract: A luminescence study of In1-xGaxAs1-yPy has been performed to determine the electronic hand structure of this quarternary alloy. Electron microprobe cathodoluminescence at 300 K was used to determine the direct Γ8v-Γlc gap and photoluminescence at 2 K for the indirect Γ8v-Xlc gap. Comparison of the experimentally determined gaps is made with the theory of Van Vechten and Bergstresser and with a simple interpolation procedure employing the experimentally determined gaps of the ternary alloy systems which constitute the boundaries of this quaternary.

Halogen containing lead activated calcium sulfide luminescent composition

Abstract: An ultraviolet emitting, cathodoluminescent, halogen and lead activated calcium sulfide composition emits as a narrow band with a peak at about 365 nanometers, under cathode ray excitation, with an increased efficiency of cathodoluminescence over the presently used oxygen dominated phosphors which emit in this region. A preferred method of preparation is set forth in which the lead and halogen are added to calcium sulfide which is fired to produce the phosphor.

Dispositif expérimental d'analyse spectrale pour l'étude de la cathodoluminescence ; Application au Zn Se

Abstract: 2014 We describe here an electronic apparatus for the automatic recording and display of spectra in pulsed cathodoluminescence experiments. In our apparatus the pulse current, the repetition rate of the pulses, the duration of each group of pulses, and the rest time between groups of pulses may all be programmed. This apparatus has been tested by performing measurements on several different cubic ZnSe crystals. REVUE DE PHYSIQUE APPLIQUÉE TOME 8, DÉCEMBRE 1973, PAGE Classification Physics Abstracts 18.40 La cathodoluminescence a contribué depuis quelques années à améliorer notre connaissance des structures de bandes et des niveaux d’impuretés dans les cristaux semi-conducteurs [1] à [6]. C’est pourquoi, nous nous sommes attachés à l’étude des transitions lumineuses émises au voisinage de la bande d’absorption par le ZnSe lorsqu’il est soumis à une excitation cathodique. A cette fin nous avons été amenés à mettre au point un dispositif expérimental permettant la mesure et le contrôle précis des conditions d’excitation des cristaux et de la répartition de l’intensité I émise par les différents points du cristal. Les principales difficultés rencontrées, les moyens mis en oeuvre pour y remédier, ainsi que les premiers résultats expérimentaux seront décrits dans cette publication. Rappelons tout d’abord que l’étude de la luminescence des cristaux ou poudres soumis à un bombardement électronique (cathodoluminescence) présente de nombreux avantages par rapport aux excitations ultraviolette ou infrarouge : densité de bombardement élevée, profondeur de pénétration des électrons primaires variable à volonté, contrôle des paramètres d’excitation, etc... Cependant, on sait que la répartition spectrale et l’intensité des raies émises par les échantillons dépendent considérablement des paramètres d’excitation et de la température. La tension d’accélé(*) 11, avenue de Villars, 78150 Le Chesnay. (**) Laboratoire de Luminescence, 9, quai Saint-Bernard, 75005 Paris 5e. ration des électrons primaires (variable entre 0 et 30 kV), intervient sur la profondeur de pénétration de ces électrons qui excitent soit des zones de surface, pour des faibles tensions, soit des zones à l’intérieur du cristal pour des tensions élevées (supérieures à 15 kV). Les autres paramètres comme le débit, la densité, et la durée plus ou moins importante de bombardement provoquent un échauffement de l’échantillon ; la largeur de la bande interdite étant étroitement liée à la température, on observe un déplacement des longueurs d’ondes de certaines transitions lumineuses émises par le cristal lorsque la température varie. C’est ce qui se produit lors de l’analyse spectrale dans un intervalle de longueurs d’onde donné. Les premières raies auront été observées alors que le cristal aura reçu une certaine énergie qui le porte à une température t ; le bombardement continu augmente son échauffement et les raies suivantes seront observées sur un cristal ne se trouvant plus dans les mêmes conditions de températures d’où résulte une erreur quant à la position et à l’intensité des raies d’un même spectre. Pour remédier à ces inconvénients il faut que les paramètres électriques d’excitation soient parfaitement définis et que la température de l’échantillon reste constante pendant la durée d’enregistrement d’un spectre. Cela a été obtenu grâce à un dispositif n’autorisant la mesure que lorsque les fluctuations (inévitables) des conditions d’excitation restent inférieures à des limites préétablies. En ce qui concerne la température, nous avons pensé limiter son influence sur les Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/rphysap:0197300804033700

Luminescence of ZnTe and Its Modulation by Infrared Radiation

Abstract: Measurements of reflectivity, photoluminescence and cathodoluminescence for various electron beam voltages were performed on p-type single crystals at liquid nitrogen, hydrogen and helium temperatures. By an application of the microreversibility principle and consideration of the reflectivity data, the nature and the energies of the transitions were determined. In addition, we identify the lines due to the annihilation of exciton-neutral defect complexes, in ground or excited state. When the luminescence is modulated by a CO2 laser (hνIR ~ 130 meV) effects are observed at liquid helium temperature. A quenching effect is observed for the free-to-bound and pair recombinations. Quenching of the luminescence due to the annihilation of exciton isoelectronic oxygen complexes is a direct corroboration of the binding-in-two-step theory.