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9 Aug 1999

Volume 75, Issue 6, pp. 745-878

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The photoluminescence from hydrogen-related species in composites of SiO2 nanoparticles

Yuri D. Glinka, Sheng-Hsien Lin, and Yit-Tsong Chen

Appl. Phys. Lett. 75, 778 (1999); http://dx.doi.org/10.1063/1.124510 (3 pages) | Cited 55 times

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Measurements of photoluminescence (PL) from composites of silica nanoparticles (the primary particle size 7 and 15 nm) as a function of heat treatment temperature show that the PL results from hydrogen-related species and thermally produced structural defects. The PL was induced by an ArF or Nd:YAG (yttrium–aluminum–garnet) laser (λexc = 193 or 266 nm). The green PL exhibits a progression with spacings of about Δν = 630 cm−1 assigned to the bending vibration of ≡Si–H on the surface of particles. The spacings increase up to Δν = 1200 cm−1 when ≡Si–H and nonbridging oxygen (≡Si–O•) form interfacial water species. © 1999 American Institute of Physics.
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78.66.Nk Insulators
61.46.-w Structure of nanoscale materials
81.07.-b Nanoscale materials and structures: fabrication and characterization
78.55.Hx Other solid inorganic materials
81.40.Gh Other heat and thermomechanical treatments
63.20.-e Phonons in crystal lattices
81.40.Tv Optical and dielectric properties related to treatment conditions

An isolated silicon single chain end-grafted onto a substrate surface

K. Furukawa, K. Ebata, and N. Matsumoto

Appl. Phys. Lett. 75, 781 (1999); http://dx.doi.org/10.1063/1.124511 (3 pages) | Cited 11 times

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We report atomic force microscopy images of one-dimensional silicon chains (polysilanes) individually bonded to a substrate surface [quartz glass (SiO2), sapphire (Al2O3), and Si(111)]. The sample was prepared by a one-to-one chemical reaction between a reactive anchor of alkylbromide on the surface and a polysilanyl lithium. We observed dot images with variable densities which depended on the reactive anchor density. Each dot, with a diameter of about 20 nm and a height of about 5 nm, corresponded to an isolated single polysilane molecule with a collapsed structure typical of usual end-grafted polymers under poor solvent conditions. © 1999 American Institute of Physics.
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81.05.Cy Elemental semiconductors
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
81.07.-b Nanoscale materials and structures: fabrication and characterization
81.16.-c Methods of micro- and nanofabrication and processing
85.35.-p Nanoelectronic devices
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)

The mechanism of micropipe nucleation at inclusions in silicon carbide

M. Dudley, X. R. Huang, W. Huang, A. Powell, S. Wang, P. Neudeck, and M. Skowronski

Appl. Phys. Lett. 75, 784 (1999); http://dx.doi.org/10.1063/1.124512 (3 pages) | Cited 42 times

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A model is presented for a possible mechanism of screw dislocation (including micropipe) nucleation in silicon carbide. The model is based on the observation of micropipe nucleation at the sites of foreign material inclusions using synchrotron white beam x-ray topography and transmission optical microscopy. It is shown that incorporation of the inclusion into the growing crystal can lead to deformation of the protruding ledge which constitutes the overgrowing layer. Accommodation of this deformation into the crystal lattice leads to the production of pairs of opposite sign screw dislocations which then propagate with the growing crystal. Evidence for the existence of such pairs of dislocations is presented. © 1999 American Institute of Physics.
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61.72.Yx Interaction between different crystal defects; gettering effect
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
61.72.Bb Theories and models of crystal defects
61.72.Qq Microscopic defects (voids, inclusions, etc.)

Characterization of the silicon on insulator film in bonded wafers by high resolution x-ray diffraction

G. M. Cohen, P. M. Mooney, E. C. Jones, K. K. Chan, P. M. Solomon, and H-S. P. Wong

Appl. Phys. Lett. 75, 787 (1999); http://dx.doi.org/10.1063/1.124513 (3 pages) | Cited 16 times

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High resolution x-ray diffraction (HRXRD) is proposed as a nondestructive tool for the characterization of the silicon on insulator (SOI) film in bonded wafers. Although the bonded stack may consist of many amorphous layers, the measured diffraction spectra only show the crystalline SOI layer, thus providing a direct measurement of the film. We have demonstrated that HRXRD is capable of accurately measuring the film thickness, the tilt of the film planes with respect to the substrate planes, and the rotation misalignment of the bonded film with respect to the carrier substrate. SOI films with thicknesses down to 30 nm were readily measured with accuracy better than 1%. It is shown that an angular separation between the layer and the substrate diffraction peaks is maintained due to an unintentional miscut which usually exists in the starting wafers used for bonding. This angular separation is unique to bonded wafers as opposed to separation by implanted oxygen (SIMOX) wafers where the layer and substrate peaks are nonseparable. Calculated diffraction spectra based on the kinematic approach showed excellent agreement with the measured diffraction. © 1999 American Institute of Physics.
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68.55.-a Thin film structure and morphology
68.35.Ct Interface structure and roughness
61.05.cp X-ray diffraction

Optical transitions in Pr-implanted GaN

J. M. Zavada, R. A. Mair, C. J. Ellis, J. Y. Lin, H. X. Jiang, R. G. Wilson, P. A. Grudowski, and R. D. Dupuis

Appl. Phys. Lett. 75, 790 (1999); http://dx.doi.org/10.1063/1.124514 (3 pages) | Cited 15 times

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Photoluminescence (PL) spectroscopy has been used to investigate praseodymium (Pr) related transitions in Pr-implanted GaN. Wurtzite GaN epilayers were grown by metalorganic chemical vapor deposition on sapphire substrates and subsequently ion implanted with Pr to a dose of 5.7×1013/cm2. The implanted samples were annealed in nitrogen to facilitate recovery from implantation related damage. Narrow PL emission bands related to 4f intrashell transitions of the trivalent Pr ion were observed near 650, 950, 1100, and 1300 nm. The dependence of PL emission on sample temperature, excitation intensity, oxygen incorporation, and annealing temperature was systematically studied. We find that the PL efficiency increases exponentially with annealing temperature up to the maximum temperature of 1050 °C applied in the current study. Furthermore, the PL emission shows no evidence of significant thermal quenching over the sample temperature range of 10–300 K. This thermal stability will have particular advantages for applications in high temperature optoelectronic devices. © 1999 American Institute of Physics.
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78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
61.72.uj III-V and II-VI semiconductors
61.72.Cc Kinetics of defect formation and annealing
71.55.Eq III-V semiconductors

Sensitization of Er3+ emission at 1.5 μm in SiO2 thermally grown on silicon by coimplantation of Yb

A. Kozanecki, K. Homewood, and B. J. Sealy

Appl. Phys. Lett. 75, 793 (1999); http://dx.doi.org/10.1063/1.124515 (3 pages) | Cited 9 times

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Effects of Yb codoping on the photoluminescence of Er3+ ions at room temperature in SiO2 films thermally grown on silicon are investigated. We demonstrate that for an excitation wavelength of 488 nm Yb ions act as efficient sensitizers of the 4I13/2–4I15/2 emission of Er3+ ions. We have found that for the fixed dose of Yb the Er3+ intensity is directly proportional to the Er concentration. Enhancement by a factor of 15 due to Yb codoping has been observed. A model of the mechanism responsible for sensitization is discussed. © 1999 American Institute of Physics.
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78.55.Hx Other solid inorganic materials
78.66.Nk Insulators
61.72.up Other materials

Phosphorus and arsenic profile control for high performance epitaxial base bipolar junction devices

R. Bashir, A. E. Kabir, and P. Westrom

Appl. Phys. Lett. 75, 796 (1999); http://dx.doi.org/10.1063/1.124516 (3 pages) | Cited 3 times

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In this study, we report on the incorporation behavior of n-type species in undoped layers grown subsequent to doped layers at low temperature (700–750 °C) reduced pressure chemical vapor deposition of silicon/silicon germanium (Si/Si1−xGex) performed in a single wafer epitaxial deposition system. Significant amounts of these species are observed even in an undoped layer grown subsequent to the doped layer. The presence of these dopants in the subsequently grown undoped layer is attributed to segregation at the moving growth interface. The arsenic segregation is confirmed to be significantly higher than phosphorus. In addition, an increase in both the phosphorus and arsenic incorporation is observed in the presence of a highly doped boron layer. © 1999 American Institute of Physics.
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85.40.Ry Impurity doping, diffusion and ion implantation technology
61.72.up Other materials
61.72.uf Ge and Si
61.72.S- Impurities in crystals
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
81.05.Cy Elemental semiconductors
81.05.Hd Other semiconductors
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
64.75.-g Phase equilibria
68.35.Fx Diffusion; interface formation
85.30.Pq Bipolar transistors
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions

Magnetophotoluminescence of stacked self-assembled InP quantum dots

R. Provoost, M. Hayne, V. V. Moshchalkov, M. K. Zundel, and K. Eberl

Appl. Phys. Lett. 75, 799 (1999); http://dx.doi.org/10.1063/1.124517 (3 pages) | Cited 15 times

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We report magnetophotoluminescence measurements of stacked layers of self-assembled InP quantum dots. With a magnetic field applied in the growth direction we have determined the exciton reduced mass from the field dependence of the photoluminescence energy. By applying a magnetic field perpendicular to the growth direction, we have analyzed the spatial confinement of the dots in the growth direction. We observe a large increase in the shift of the exciton energy between 0 and 50 T when the thickness of the GaInP spacer layer between the dots is reduced from 8 to 4 nm. This indicates a decrease in spatial confinement in the growth direction which we attribute to strong electronic coupling between vertically stacked dots. © 1999 American Institute of Physics.  
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78.66.Fd III-V semiconductors
78.55.Cr III-V semiconductors
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
78.20.Ls Magneto-optical effects
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
71.35.Ji Excitons in magnetic fields; magnetoexcitons

Mn-doped ZnS nanoparticles as efficient low-voltage cathodoluminescent phosphors

A. D. Dinsmore, D. S. Hsu, H. F. Gray, S. B. Qadri, Y. Tian, and B. R. Ratna

Appl. Phys. Lett. 75, 802 (1999); http://dx.doi.org/10.1063/1.124518 (3 pages) | Cited 38 times

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We have synthesized nanoparticles of ZnS doped with Mn for potential use as cathodoluminescent phosphors in field-emission displays (FEDs). We show that the cathodoluminescent efficiency of particles ⩽100 nm in diameter is within 40% of that of a commercial (micron-sized) phosphor when the electron-beam energy ranges between 500 and 3500 eV. The nanoparticles exhibit less current saturation than larger-sized phosphors, an important feature for use in FEDs. Furthermore, the nanoparticles were annealed at just 535 °C, hundreds of degrees below the processing temperatures of standard phosphors. Finally, we discuss the effect of the particle surface on low-voltage luminous efficiency. © 1999 American Institute of Physics.
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78.60.Hk Cathodoluminescence, ionoluminescence
85.45.Fd Field emission displays (FEDs)
61.46.-w Structure of nanoscale materials
81.07.-b Nanoscale materials and structures: fabrication and characterization
81.05.Dz II-VI semiconductors
61.72.Cc Kinetics of defect formation and annealing
81.40.Gh Other heat and thermomechanical treatments

Freely migrating defects in ion-irradiated Cu3Au

L. C. Wei, E. Lang, C. P. Flynn, and R. S. Averback

Appl. Phys. Lett. 75, 805 (1999); http://dx.doi.org/10.1063/1.124519 (3 pages) | Cited 9 times

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The efficiency of producing freely migrating vacancy defects in irradiated Cu3Au was examined using electrical resistivity measurements of radiation-induced ordering on highly perfect single-crystal films. Relative efficiencies for He, Ne, and Ar bombardments at different ion energy and specimen temperature were obtained. The ratio of the efficiencies of 0.6 MeV Ne to He increased with temperature from ∼ 0.25 at 340 K to a saturation value of ∼ 0.40 at 520 K. For Ar and He, the ratio increased from ∼ 0.11 at 360 K to ∼ 0.18 at 540 K. Estimates indicate that about half of all defects created in cascades are freely migrating. © 1999 American Institute of Physics.
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61.80.Jh Ion radiation effects
61.82.Bg Metals and alloys
61.72.J- Point defects and defect clusters
66.30.Lw Diffusion of other defects
73.61.At Metal and metallic alloys
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.

Inversion of wurtzite GaN(0001) by exposure to magnesium

V. Ramachandran, R. M. Feenstra, W. L. Sarney, L. Salamanca-Riba, J. E. Northrup, L. T. Romano, and D. W. Greve

Appl. Phys. Lett. 75, 808 (1999); http://dx.doi.org/10.1063/1.124520 (3 pages) | Cited 82 times

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Magnesium incorporation during the molecular-beam epitaxy growth of wurtzite GaN is found to invert the Ga-polar (0001) face to the N-polar face. The polarity is identified based on the two different sets of reconstructions seen on the film prior to and after about 1 monolayer Mg exposure. The inversion boundary is seen to lie on the (0001) plane from transmission electron microscopy images, and a structural model is presented for the inversion. On the Ga-polar face, Mg is also seen to stabilize growth in the N-rich regime. © 1999 American Institute of Physics.
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68.35.Rh Phase transitions and critical phenomena
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
61.72.uj III-V and II-VI semiconductors
68.35.B- Structure of clean surfaces (and surface reconstruction)
81.05.Ea III-V semiconductors

Production and annealing of electron irradiation damage in ZnO

D. C. Look, D. C. Reynolds, J. W. Hemsky, R. L. Jones, and J. R. Sizelove

Appl. Phys. Lett. 75, 811 (1999); http://dx.doi.org/10.1063/1.124521 (3 pages) | Cited 149 times

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High-energy (>1.6 MeV) electrons create acceptors and donors in single-crystal ZnO. Greater damage is observed for irradiation in the [0001] direction (Zn face) than in the [000math] direction (O face). The major annealing stage occurs at about 300–325 °C, and is much sharper for defects produced by Zn-face irradiation, than for those resulting from O-face irradiation. The defects appear to have a chain character, rather than being simple, near-neighbor vacancy/interstitial Frenkel pairs. These experiments suggest that ZnO is significantly more “radiation hard” than Si, GaAs, or GaN, and should be useful for applications in high-irradiation environments, such as electronics in space satellites. © 1999 American Institute of Physics.
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61.82.Fk Semiconductors
61.80.Fe Electron and positron radiation effects
61.72.Cc Kinetics of defect formation and annealing
71.55.Gs II-VI semiconductors
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