UScholar Works
 
Filters: Journal Title: "Applied Physics Letters" Collection: "ir_uspace"
1 - 25 of 35
Number of results to display per page
CreatorTitleDescriptionSubjectDate
1 Tiwari, AshutoshFerromagnetism in Co doped CeO2: observation of giant magnetic moment with a high Curie temperatureWe report room temperature ferromagnetism in single crystal Ce1−xCoxO2−δ (x≤0.05) films deposited on a LaAlO3(001) substrate. Films were grown by a pulsed laser deposition technique and were thoroughly characterized using x-ray diffraction, high-resolution transmission electron microscopy cou...CeO2; Cobalt2006
2 Tiwari, AshutoshEpitaxial growth and properties of Zn1-xVxO diluted magnetic semiconductor thin filmsHere we report systematic studies on the epitaxial growth and properties of Zn1−xVxO[x=0.001-0.2] thin films deposited onto sapphire c-plane single crystals. The thin films were deposited using pulsed laser deposition technique and were found to be epitaxial in nature. X-ray diffraction and high ...ZnO; Vanadium2005
3 Lupton, John MarkOn-chain defect emission in electroluminescent polyfluorenesWe present time-resolved photoluminescence measurements on a range of poly- and oligofluorenes with different molecular weights in both dilute solution and thin films. The commonly observed parasitic broad green emission band, which has previously been attributed to an excimer, is identified in all...Defect emission; Parasitic broad green emission band2002
4 Williams, Clayton C.Measurement of in-plane magnetization by force microscopyWe present data which show that the magnetic force microscope is capable of detecting the component of the magnetic field parallel to the surface of a sample under study. Images of bits in a Co-alloy thin-film disk and of laser-written bits in a TbFe film were taken with a magnetized tip tilted at ...Co-alloy disc; Magnetization1988
5 Williams, Clayton C.High resolution photothermal laser probeAt frequencies near 1 GHz, the acoustic wavelength in argon gas becomes half that of visible light, making possible collinear Bragg scattering of laser light by the sound. This acousto-optic interaction has been used to detect photothermally generated acoustic power at the surface of solids. This ne...Photothermal laser probe; Silicon wafer1984
6 Williams, Clayton C.Noise reduction technique for scanning tunneling microscopyNoise stemming from mechanical vibration, electronic noise, or low frequency (l / f power spectrum) inherent in the tunneling process, often limits the resolution, speed, or range of application of scanning tunneling microscopy (STM). We demonstrate a technique for minimizing the effect of these noi...Noise reduction; Dithering; Graphite1988
7 Tiwari, AshutoshCuBO2: a p-type transparent oxideThe authors report the synthesis of CuBO2, a p-type transparent oxide belonging to Cu-delafossite family. High quality thin films of CuBO2 were deposited on c-plane sapphire substrates by pulsed laser deposition technique. Detailed structural, optical, and electrical characterizations on these films...Transparent conducting oxides; Delafossite series; CuBO22007
8 Scarpulla, MichaelFerromagnetic Ga1-xMnxAs produced by ion implantation and pulsed-laser meltingWe demonstrate the formation of ferromagnetic Ga1-xMnxAs films by Mn ion implantation into GaAs followed by pulsed-laser melting. Irradiation with a single excimer laser pulse results in the epitaxial regrowth of the implanted layer with Mn substitutional fraction up to 80% and effective Curie tempe...Gallium arsenide; Ferromagnetic semiconductors; Remanent magnetization2003
9 Williams, Clayton C.Mapping of mobile charges on insulator surfaces with the electrostatic force microscopeMigration of surface ions in lateral fields on insulator surfaces may modify the electrical characteristics of underlying semiconductor structures causing device instabilities. A high sensitivity electrostatic force microscope is used to image the movement and spatial distribution of surface ions on...Insulator surfaces; Surface ions; Electrostatic force microscope1993
10 Vardeny, Zeev ValentineFemtosecond dynamics of the nonlinear optical response in polydiethynylsilaneWe have measured the femtosecond dynamics of the nonlinear optical response xc3' in polydiethynylsilane ( C4H2SiBu2)x, a novel class of r-conjugated polymers incorporating Si, using degenerate four-wave mixing and photoinduced absorption techniques. In resonance conditions at 620 nm we found x (3) ...Polydiethynylsilane; Femtosecond dynamics; Nonlinear optical response; Pi-conjugated polymers1991
11 Lupton, John MarkFrequency up-conversion as a temperature probe of organic opto-electronic devicesFrequency up-conversion is demonstrated in a polyfluorene-based conjugated polymer. Up-converted emission is observed upon excitation to the red of the 0-0 luminescence band. The emission intensity depends strongly on temperature and provides an accurate probe of the operating temperature of organic...Frequency up-conversion; Organic opto-electronic devices2002
12 Scarpulla, MichaelMutual passivation of group IV donors and nitrogen in diluted GaNxAs1 x alloysWe demonstrate the mutual passivation phenomenon of Ge donors and isovalent N in highly mismatched alloy GaNxAs1-x doped with Ge. Layers of this alloy were formed by the sequential implantation of Ge and N ions followed by pulsed laser melting and rapid thermal annealing. The mutual passivation effe...Highly mismatched alloys; Passivation; Gallium arsenide2003
13 Williams, Clayton C.Scanning thermal profilerA new high-resolution profilometer has been demonstrated based upon a noncontacting nearfield thermal probe. The thermal probe consists of a thermocouple sensor with dimensions approaching 100 nm. Profiling is achieved by scanning the heated sensor above but close to the surface of a solid. The con...Thermal probe; Scanning thermal profiler1986
14 Williams, Clayton C.Lateral dopant profiling with 200 nm resolution by scanning capacitance microscopyMeasurement of dopant density in silicon with lateral resolution on the 200 nm scale has been demonstrated with a near-field capacitance technique. The technique is based upon the measurement of local capacitance between a 100 nm tip and a semiconducting surface. Lateral dopant imaging is achieved b...Dopant profile; Doping density; Scanning capacitance microscopy1989
15 Williams, Clayton C.Scanning capacitance microscopy on a 25 nm scaleA near-field capacitance microscope has been demonstrated on a 25 nm scale. A resonant circuit provides the means for sensing the capacitance variations between a sub-lGO-nra tip and surface with a sensitivity of 1X 10 19 F in a I kHz bandwidth. Feedback control is used to scan the tip at constant g...Scanning capacitance microscopy1989
16 Vardeny, Zeev ValentineAmplified spontaneous emission and lasing in conducting polymers and fluorescent dyes in opals as photonic crystalsSpectral narrowing of photoluminescence (PL) and evolution of sharp emission lines upon optical excitation have been observed in opals made of SiO2 spheres infiltrated with conducting polymers such as OOPPV and MDDOPPV and also fluorescent dyes such as rhodamine 6G, NK-3483, and coumarin 120. Their ...Amplified spontaneous emission; Lasing; Fluorescent dyes1999
17 Lupton, John MarkBright electroluminescence from a conjugated dendrimerPhotoluminescence and electroluminescence (EL) from a conjugated dendrimer consisting of three distyrylbenzene units linked by a central nitrogen atom as core and meta-linked biphenyl units as dendrons were investigated. The conjugated dendrimer emits green light and shows photoluminescence quantum ...Conjugated dendrimer2002
18 Liu, FengFabricating artificial nanowells with tunable size and shape by using scanning tunneling microscopyThe authors report a method of precisely fabricating the large-scale nanocrystals with well-defined shape and size. The (111) oriented Pb islands deposited on Si(111)-7x7 substrate were investigated with a manipulation technique based on scanning tunneling microscopy. By applying a series of voltage...Artificial nanowells2006
19 Tiwari, AshutoshFerromagnetism in Cu-doped ZnO films: role of charge carriersWe report the observation of room temperature ferromagnetism in Cu-doped (5%) ZnO films grown on c-plane sapphire substrates. Films were prepared by pulsed laser deposition technique and were thoroughly characterized using several state-of-the-art characterization techniques. Hall measurements sho...Charge carriers2008
20 Tiwari, AshutoshGrowth and characterization of TaN/TiN superlattice structuresEpitaxial B1 NaCl-structured TaN(3 nm)/TiN(2 nm) superlattice structures were grown on Si(100) substrates with a TiN buffer layer, using pulsed-laser deposition. A special target assembly was used to manipulate the thickness of each layer. X-ray diffraction, transmission electron microscopy, and ...Diffusion barriers; Copper diffusion; Tantalum nitride2003
21 Lupton, John MarkMolecular thermometer based on long-lived emission from platinum octaethyl porphyrinA highly sensitive molecular thermometer based on platinum octaethyl porphyrin, which can be employed in a range of environments, is presented. The thermal activation of the emission spectrum results in a change in emission intensity by an order of magnitude over a temperature range of 45 K about ro...Molecular thermometer; Platinum octaethyl porphyrin2002
22 Scarpulla, MichaelNear-infrared absorption and semimetal-semiconductor transition in 2 nm ErAs nanoparticles embedded in GaAs and AlAsWe report strong near-infrared absorption peaks in epitaxial films of GaAs and AlAs containing approximately 0.5-5% of the semimetal ErAs. The energy of the resonant absorption peak can be changed from 0.62 to 1.0 eV (2.2-1.4 μm) by variation of the ErAs volume fraction and the substrate temperatu...Near-infrared absorption; Semimetal-semiconductor transition; GaAs; AlAs; ErAs; Gallium arsenide; Aluminum arsenide2008
23 Williams, Clayton C.Single-electron manipulation to and from a SiO2 surface by electrostatic force microscopyOccupation of individual electron states near the surface of a SiO2 film is controlled by reversible single-electron tunneling to or from a metallic electrostatic force microscope probe. By switching the polarity of an applied dc bias between the probe and the sample to adjust the Fermi energy of ...2005
24 Stringfellow, Gerald B.; Shurtleff, James KevinSurfactant effects on doping of GaAs grown by organometallic vapor phase epitaxyRecently, the addition of the isoelectronic surfactant Sb during organometallic vapor phase epitaxy (OMVPE) of GaInP was shown to eliminate ordering, resulting in a significant change in the band gap energy. These results suggest that surfactants added during growth could have profound affects on ot...Gallium arsenide; Surfactants; Semiconductors2001
25 Lupton, John MarkBragg scattering from periodically microstructured light emitting diodesWe present a simple method of generating a periodic wavelength scale structure in the optically active layer of a light emitting diode. This is achieved by solution deposition of a light emitting polymer on top of a corrugated substrate. The periodic structure allows waveguide modes normally trapped...Bragg scattering; Periodic wavelength scale structure2000
1 - 25 of 35