APL Nameplate
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter iResearch App Facebook

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

22 Oct 2001

Volume 79, Issue 17, pp. 2681-2850

Page 1 of 3 Pages Next Page | Jump to Page
back to top
RSS Feeds

Near-field microscopy and spectroscopy of third-harmonic generation and two-photon excitation in nonlinear organic crystals

Yuzhen Shen, Jacek Swiatkiewicz, Przemyslaw Markowicz, and Paras N. Prasad

Appl. Phys. Lett. 79, 2681 (2001); http://dx.doi.org/10.1063/1.1412433 (3 pages)

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Near-field microscopy and spectroscopy of third-harmonic generation and two-photon excitation are demonstrated on a subdiffraction-limited scale. Near-field measurements of both the intensity dependence and the spectral dependence are performed on nonlinear organic nanocrystals of 4-(N, N-diethylamino)-β-nitrostyrene. The in-plane local anisotropies of third-order susceptibilities are observed, which is revealed to be associated to two-photon allowed π–electron transition. The local spectra exhibit the crystal symmetry on a nanometric scale. © 2001 American Institute of Physics.
Show PACS
42.70.Jk Polymers and organics
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.65.An Optical susceptibility, hyperpolarizability

Wide-range-tunable laterally coupled distributed feedback lasers based on InGaAsP–InP

M. Müller, M. Kamp, A. Forchel, and J.-L. Gentner

Appl. Phys. Lett. 79, 2684 (2001); http://dx.doi.org/10.1063/1.1404397 (3 pages) | Cited 10 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have investigated tunable distributed feedback (DFB) lasers based on InGaAsP quantum wells grown by molecular-beam epitaxy. Two-section tunable DFB lasers were fabricated by patterning laterally gain coupling binary superimposed gratings perpendicular to the ridge waveguide. Side mode suppression ratios of up to 42 dB have been achieved. The tuning range covers 25 nm. © 2001 American Institute of Physics.
Show PACS
42.55.Px Semiconductor lasers; laser diodes
42.60.By Design of specific laser systems
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
78.66.Fd III-V semiconductors

Dynamics of the second-order nonlinearity in thermally poled silica glass

D. Faccio, V. Pruneri, and P. G. Kazansky

Appl. Phys. Lett. 79, 2687 (2001); http://dx.doi.org/10.1063/1.1394948 (3 pages) | Cited 21 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We study the temporal evolution of both the second-order nonlinear coefficient and of the nonlinear thickness in thermally poled silica-glass slides by using a high-resolution all-optical technique. A time delay in the nonlinearity formation is observed, followed by an increase to a maximum, and a final decrease. The thickness is shown to increase at a rate that differs significantly from that reported for the corresponding ionic charge fronts. Our measurements also show strong dependencies on sample thickness and these can be attributed to different electric fields in the depletion region. © 2001 American Institute of Physics.
Show PACS
42.70.Ce Glasses, quartz
77.22.Ej Polarization and depolarization
77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.
42.65.-k Nonlinear optics
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials

Surface-emitting channel drop filters using single defects in two-dimensional photonic crystal slabs

Alongkarn Chutinan, Masamitsu Mochizuki, Masahiro Imada, and Susumu Noda

Appl. Phys. Lett. 79, 2690 (2001); http://dx.doi.org/10.1063/1.1413720 (3 pages) | Cited 58 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report a theoretical analysis of trapping and emission of photons by a single defect in a two-dimensional photonic crystal slab. We show that the tuning of emission wavelength is possible by selecting appropriate geometry of structure while keeping the emission efficiency maximal. The results suggest the possibility of applying it to ultra-small channel add/drop device in wavelength division multiplexed optical communications. © 2001 American Institute of Physics.
Show PACS
42.70.Qs Photonic bandgap materials
42.79.Sz Optical communication systems, multiplexers, and demultiplexers
42.79.Ci Filters, zone plates, and polarizers
42.82.Et Waveguides, couplers, and arrays

Strain-induced channel waveguiding in bulk sapphire substrates

Mingjiao Liu and Hong Koo Kim

Appl. Phys. Lett. 79, 2693 (2001); http://dx.doi.org/10.1063/1.1413221 (3 pages) | Cited 3 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report on the two-dimensional confinement of light in the channel region of a bulk sapphire substrate, which was formed by utilizing the photoelastic effect in sapphire induced by a sputter-deposited SiO2 film. The experimental result, combined with the simulation results, shows that the sputter-deposited SiO2 films are compressively stressed up to 10 GPa level and that a 1.0-μm-thick film, for example, induces an index change of 5×10−3 in sapphire in the vertical direction. This amount of index change is found sufficient to support a fundamental mode at wavelengths of 1.54 μm or below. © 2001 American Institute of Physics.
Show PACS
42.79.Gn Optical waveguides and couplers
42.82.Et Waveguides, couplers, and arrays
81.15.Cd Deposition by sputtering
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
78.20.hb Piezo-optical, elasto-optical, acousto-optical, and photoelastic effects

206 W continuous-wave TEM00 mode 1064 nm beam generation by a laser-diode-pumped Nd:YAG rod laser amplifier

Susumu Konno, Shuichi Fujikawa, and Koji Yasui

Appl. Phys. Lett. 79, 2696 (2001); http://dx.doi.org/10.1063/1.1409332 (2 pages) | Cited 6 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We demonstrate a 206 W 1064 nm beam generation at a beam quality of M2 = 1.34 with a Nd:YAG laser amplifier system. We also report on an efficient 150 W TEM00 mode diode-pumped Nd:YAG rod laser. © 2001 American Institute of Physics.
Show PACS
42.55.Rz Doped-insulator lasers and other solid state lasers
42.60.Jf Beam characteristics: profile, intensity, and power; spatial pattern formation
42.60.Pk Continuous operation
back to top
RSS Feeds

Reduction of microtrenching and island formation in oxide plasma etching by employing electron beam charge neutralization

M. Watanabe, D. M. Shaw, and G. J. Collins

Appl. Phys. Lett. 79, 2698 (2001); http://dx.doi.org/10.1063/1.1413726 (3 pages) | Cited 11 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
During plasma etching of oxide thin-film patterns, nonuniform charge buildup within etching features results in formation of microtrenches. Near the etch endpoint, the underlying film layer adjacent to the feature edges is exposed first, leaving an oxide island in the feature center and potentially causing underlayer damage before the endpoint is reached. Herein, a directional electron flux is added to the plasma ion flux incident on the etching substrate with the goal of minimizing microtrenching and oxide island formation. Scanning electron microscopic images of patterns etched with added electron irradiation show a reduction in microtrenching and oxide island formation as compared to patterns etched under identical conditions without electron irradiation. A computer simulation shows that the added electron irradiation reduces microtrenching by allowing more uniform ion flux to reach the feature bottom. © 2001 American Institute of Physics.
Show PACS
52.77.Bn Etching and cleaning
81.65.Cf Surface cleaning, etching, patterning
61.80.Fe Electron and positron radiation effects
back to top
RSS Feeds

Inhomogeneous broadening in quantum dots with ternary aluminum alloys

C. Nì Allen, P. Finnie, S. Raymond, Z. R. Wasilewski, and S. Fafard

Appl. Phys. Lett. 79, 2701 (2001); http://dx.doi.org/10.1063/1.1410333 (3 pages) | Cited 13 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We study how the optical properties of InAs self-assembled quantum dots (QDs) grown on GaAs substrate are affected when using AlGaAs barriers to increase the carrier confinement. The inhomogeneous broadening of the QD ensemble is found to increase when ternary aluminum alloys are used next to or within the QDs. By growing thin GaAs spacers to separate the QDs from the AlGaAs barriers, we obtain QD ensembles which exhibit little photoluminescence quenching and well-defined excited states up to room temperature. Postgrowth rapid thermal annealing is then used to intermix these InAs/GaAs/AlGaAs QDs and diffuse the Al towards the QDs. In contrast with QDs having thick binary GaAs barriers, the inhomogeneous broadening of QDs with nearby AlGaAs barriers is not decreased with intermixing, leading to unresolved excited state peaks when the interdiffusion length becomes comparable to the GaAs spacer thickness. © 2001 American Institute of Physics.
Show PACS
78.67.Hc Quantum dots
73.21.La Quantum dots
78.55.Cr III-V semiconductors
68.35.Fx Diffusion; interface formation
68.65.Hb Quantum dots (patterned in quantum wells)
81.07.Ta Quantum dots
61.72.Cc Kinetics of defect formation and annealing

Distinguishing surface and bulk contributions to third-harmonic generation in silicon

P. N. Saeta and N. A. Miller

Appl. Phys. Lett. 79, 2704 (2001); http://dx.doi.org/10.1063/1.1412434 (3 pages) | Cited 7 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report measurements of third-harmonic generation from ultrathin crystalline silicon layers of gradually varying thickness. Both the angular and thickness dependence of the third-harmonic light generated in transmission at normal incidence are consistent with negligible surface contribution to third-harmonic generation in silicon, even under tight focusing. This work illustrates a method for distinguishing surface and bulk contributions to harmonic generation. © 2001 American Institute of Physics.
Show PACS
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation

Millisecond dynamics of thermal expansion of mechanically controllable break junction electrodes studied in the tunneling regime

O. Yu. Kolesnychenko, A. J. Toonen, O. I. Shklyarevskii, and H. van Kempen

Appl. Phys. Lett. 79, 2707 (2001); http://dx.doi.org/10.1063/1.1412281 (3 pages) | Cited 5 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The thermal expansion dynamics of W, Pt–Ir, and Au mechanically controllable break junction electrodes was studied in the millisecond range. By measuring a transient tunnel current as a function of time, we found that, at low temperatures, the electrode elongation Δs ∼ t1/2 due to the large values of thermal diffusivity of metals. The magnitude of Δs varies in direct proportion to the power P dissipated in the electrodes. © 2001 American Institute of Physics.
Show PACS
07.79.Cz Scanning tunneling microscopes
65.40.De Thermal expansion; thermomechanical effects
62.20.F- Deformation and plasticity
81.40.Lm Deformation, plasticity, and creep

Periodic composition modulations in InGaN epitaxial layers

A. N. Westmeyer and S. Mahajan

Appl. Phys. Lett. 79, 2710 (2001); http://dx.doi.org/10.1063/1.1411984 (3 pages) | Cited 17 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
InGaN epitaxial layers grown by metalorganic chemical vapor deposition were investigated in order to understand the occurrence of composition modulations in the GaN–InN system. The In contents of the samples were determined to be x = 0.21 and 0.31. Transmission electron microscopy was performed on [0001], [10math0], and [11math0] zone-axis specimens. Plan-view images display a domain structure, representing regions in which the directions of the modulations differ. Intersections between domains occur in 〈10math0〉, and 〈11math0〉, and other directions. Satellite spots appear in selected-area diffraction patterns. These observations can be explained by diffraction effects resulting from periodic composition modulations. An equation was derived relating the spacing between the satellites and the reflections to the wavelength of the modulations in the wurtzite structure. The sample with x = 0.21 had a wavelength of λ = 3.1±1.3 nm and the one with x = 0.31 had λ = 3.2±1.3 nm. Since Young’s modulus is isotropic in the (0001) plane, no particular direction is favored for the modulations based on strain energy considerations. This result is consistent with the observation of the variously oriented domains and satellites. © 2001 American Institute of Physics.
Show PACS
68.55.Nq Composition and phase identification
68.55.-a Thin film structure and morphology
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.05.Ea III-V semiconductors
68.37.Lp Transmission electron microscopy (TEM)

Effects of step-graded AlxGa1−xN interlayer on properties of GaN grown on Si(111) using ultrahigh vacuum chemical vapor deposition

Min-Ho Kim, Young-Gu Do, Hyon Chol Kang, Do Young Noh, and Seong-Ju Park

Appl. Phys. Lett. 79, 2713 (2001); http://dx.doi.org/10.1063/1.1412824 (3 pages) | Cited 42 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report the growth of high-quality GaN on a Si(111) substrate using a five step-graded AlxGa1−xN (x = 0.87–0.07) interlayer between GaN epilayer and AlN buffer layer by ultrahigh vacuum chemical vapor deposition. The crack density and the surface roughness of the GaN layer grown on the graded AlxGa1−xN interlayer were substantially reduced, compared to those of GaN grown on an AlN buffer layer. Significant improvement in the structural and optical properties of the GaN layer was also achieved by the use of a graded interlayer. These results are attributed to the decrease of the lattice mismatch between GaN and AlN layer, and the reduction of the thermal stress by the graded interlayer. © 2001 American Institute of Physics.
Show PACS
81.05.Ea III-V semiconductors
68.55.-a Thin film structure and morphology
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.15.Kk Vapor phase epitaxy; growth from vapor phase
78.66.Fd III-V semiconductors
62.20.M- Structural failure of materials
78.55.Cr III-V semiconductors
68.60.Bs Mechanical and acoustical properties

Surface hydroxyl formation on vacuum-annealed TiO2(110)

Toshiaki Fujino, Mitsuhiro Katayama, Katsuhiko Inudzuka, Tomohisa Okuno, Kenjiro Oura, and Takashi Hirao

Appl. Phys. Lett. 79, 2716 (2001); http://dx.doi.org/10.1063/1.1412427 (3 pages) | Cited 13 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The change in surface composition and structure of a rutile TiO2(110) surface during thermal annealing in an ultrahigh vacuum was studied by coaxial impact–collision ion scattering spectroscopy and time-of-flight elastic recoil detection analysis. When the clean TiO2(110) surface with a 1×1 bridging-oxygen-rows structure was obtained by annealing at 730 °C, about one monolayer of hydrogen atoms still resided on the surface. These hydrogen atoms were assigned to surface hydroxyls as an ingredient of the TiO2(110)1×1 structure, which was formed in the self-restoration process of surface oxygen vacancy defects by dissociative adsorption of water molecules during thermal annealing. © 2001 American Institute of Physics.
Show PACS
68.35.Dv Composition, segregation; defects and impurities
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.43.-h Chemisorption/physisorption: adsorbates on surfaces
61.72.Cc Kinetics of defect formation and annealing
81.40.Gh Other heat and thermomechanical treatments
68.49.Sf Ion scattering from surfaces (charge transfer, sputtering, SIMS)
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces

High-temperature metastability of cubic spinel Si3N4

T. Sekine and T. Mitsuhashi

Appl. Phys. Lett. 79, 2719 (2001); http://dx.doi.org/10.1063/1.1412826 (3 pages) | Cited 13 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The metastability of cubic spinel Si3N4 has been investigated at high temperature, up to about 1800 K, and in Ar atmosphere by quench experiments and differential thermal analyses coupled with thermogravimetry. The results indicate that the enthalpy change from spinel-type Si3N4 to β-Si3N4 is −29.2±3.5 kJ/mol and that the transformation starts at 1670 K. The high-temperature metastability of spinel Si3N4 may provide various directions for industrial applications. © 2001 American Institute of Physics.
Show PACS
81.30.Hd Constant-composition solid-solid phase transformations: polymorphic, massive, and order-disorder
64.70.K- Solid-solid transitions
82.60.Fa Heat capacities and heats of phase transitions
65.40.G- Other thermodynamical quantities

Comparison of light- and heavy-ion-irradiated quantum-wells for use as ultrafast saturable absorbers

J. Mangeney, H. Choumane, G. Patriarche, G. Leroux, G. Aubin, J. C. Harmand, J. L. Oudar, and H. Bernas

Appl. Phys. Lett. 79, 2722 (2001); http://dx.doi.org/10.1063/1.1408602 (3 pages) | Cited 18 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have compared light- and heavy-ion irradiation of InGaAs/InAlAs multiple-quantum wells for ultrafast saturable absorption applications. Under heavy-ion impacts, defect clusters were produced, as observed via transmission electronic microscopy. By contrast, in proton-irradiated samples, only point defects were formed. Nonlinear absorption measurements were performed with excitonic resonance pumping. The relaxation time of absorption saturation (minimum value 2 ps) did not depend on the irradiating ion, and was practically independent of the pulse repetition rate (up to 10 GHz) and optical excitation fluence (0.1 mJ/cm2). We conclude that irradiating multiple-quantum wells with light ions is as effective as using heavy ions, when fabricating ultrafast saturable absorber devices operating at high bit rate and near bandedge wavelength. © 2001 American Institute of Physics.
Show PACS
78.67.De Quantum wells
73.21.Fg Quantum wells
78.47.-p Spectroscopy of solid state dynamics
42.50.Md Optical transient phenomena: quantum beats, photon echo, free-induction decay, dephasings and revivals, optical nutation, and self-induced transparency
71.35.-y Excitons and related phenomena
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
61.80.Jh Ion radiation effects
61.82.Fk Semiconductors

Hillock formation on copper at room temperature by cleaning in ammonia vapor

P. J. Herley, A. L. Greer, and W. Jones

Appl. Phys. Lett. 79, 2725 (2001); http://dx.doi.org/10.1063/1.1412432 (3 pages) | Cited 1 time

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Rapidly solidified copper particles are formed by electron-beam decomposition of copper hydride. When exposed to aqueous ammonia vapor at room temperature, the surface of the particles is cleaned and etched, and it develops hillocks and incipient whiskers. Damage of this kind is associated with compressive stress in integrated-circuit metallization. The development of such damage without any elevated temperature appears facilitated by the surface cleaning, and may have implications for device processing. Some links with surface diffusivity and its proposed role in device reliability are also explored. © 2001 American Institute of Physics.
Show PACS
81.65.Cf Surface cleaning, etching, patterning
81.05.Bx Metals, semimetals, and alloys
85.40.Ls Metallization, contacts, interconnects; device isolation
68.35.B- Structure of clean surfaces (and surface reconstruction)
85.30.-z Semiconductor devices

Tellurium antisites in CdZnTe

Muren Chu, Sevag Terterian, David Ting, C. C. Wang, H. K. Gurgenian, and Shoghig Mesropian

Appl. Phys. Lett. 79, 2728 (2001); http://dx.doi.org/10.1063/1.1412588 (3 pages) | Cited 37 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The electrical properties of CdTe and Cd1−xZnxTe crystals grown under excess tellurium by a modified Bridgman technique are critically dependent on the zinc content. Below an x value of 0.07, the as-grown CdZnTe crystals are n type while, above this value, CdZnTe crystals are p type. The origin of the shallow donor level at 0.01 eV below the conduction band is most likely singly ionized Te antisites (Te at Cd sites). The origin of the deep donor level at 0.75 eV below the conduction band is therefore doubly ionized tellurium antisites. Based on this model, the conduction type of CdZnTe crystals is determined by the results of compensation between the shallow donors of Te antisites and the shallow acceptors of Cd vacancies. High resistivity Cd0.9Zn0.1Te crystals are produced by compensating the p-type crystals with indium impurity at a low doping level of 1–5×1015 cm−3. At room temperature, CdZnTe radiation detectors can resolve the six low energy peaks in the 241Am spectrum, a performance comparable to that of the best CdZnTe detectors reported. © 2001 American Institute of Physics.
Show PACS
71.55.Gs II-VI semiconductors
81.05.Dz II-VI semiconductors
61.72.J- Point defects and defect clusters

Hydrostatic-pressure dependence of the photoconductivity of single-crystal pentacene and tetracene

Zhenlin Rang, Anders Haraldsson, Dong M. Kim, P. Paul Ruden, Marshall I. Nathan, Reid J. Chesterfield, and C. Daniel Frisbie

Appl. Phys. Lett. 79, 2731 (2001); http://dx.doi.org/10.1063/1.1410878 (3 pages) | Cited 25 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Pentacene and tetracene show readily observable photoconductivity when illuminated with light in the blue part of the visible spectrum. We measured the change of photoconductivity with hydrostatic pressure in single-crystal samples of both materials. Possible mechanisms for the observed increase in photoconductivity with pressure are discussed. We conclude that a carrier-mobility increase under pressure is most likely to cause the increase in photoconductivity in the case of pentacene. For tetracene, changes in the absorption spectrum in the range of the excitation wavelengths may also be significant. We also observe a phase transition near 0.3 GPa in tetracene, in agreement with previous results. © 2001 American Institute of Physics.
Show PACS
72.40.+w Photoconduction and photovoltaic effects
72.80.Le Polymers; organic compounds (including organic semiconductors)
62.50.-p High-pressure effects in solids and liquids

Influence of microstructure on the carrier concentration of Mg-doped GaN films

L. T. Romano, M. Kneissl, J. E. Northrup, C. G. Van de Walle, and D. W. Treat

Appl. Phys. Lett. 79, 2734 (2001); http://dx.doi.org/10.1063/1.1413222 (3 pages) | Cited 32 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Room-temperature Hall effect measurements of (0001) Mg-doped GaN films grown on sapphire substrates by metalorganic chemical vapor deposition show a reduction in hole concentration for Mg concentrations greater than 1020 cm−3. A combination of secondary ion mass spectrometry and transmission electron microscopy indicates a steadily increasing Mg incorporation during growth and the formation of inversion domains at these high concentrations. We discuss mechanisms that could give rise to a reduction of the hole concentration at high Mg doping levels. © 2001 American Institute of Physics.
Show PACS
73.61.Ey III-V semiconductors
68.55.-a Thin film structure and morphology
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
back to top
RSS Feeds

Improved mobilities and resistivities in modulation-doped p-type AlGaN/GaN superlattices

Erik L. Waldron, John W. Graff, and E. Fred Schubert

Appl. Phys. Lett. 79, 2737 (2001); http://dx.doi.org/10.1063/1.1410340 (3 pages) | Cited 28 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The transport properties of modulation, shifted modulation, and uniformly doped Al0.20Ga0.80N/GaN superlattices are presented. The modulation-doped sample is doped only in the AlGaN barriers. The shifted-modulation-doped sample has its dopants shifted by one-quarter period. Measurements reveal a strong improvement in mobility and resistivity for the modulation-doped and shifted-modulation-doped structures versus the uniformly doped structure. The modulation-doped sample has a mobility of 9.2 and 36 cm2/V s at 300 and 90 K respectively and a very low resistivity of 0.20 and 0.068 Ω cm at 300 and 90 K, respectively. Capacitance–voltage profiling shows multiple two-dimensional hole gases. The results are consistent with a reduction of neutral impurity scattering for modulation-doped structures as compared to uniformly doped structures. © 2001 American Institute of Physics.
Show PACS
73.63.-b Electronic transport in nanoscale materials and structures
72.80.Ey III-V and II-VI semiconductors
72.20.Fr Low-field transport and mobility; piezoresistance
73.50.Dn Low-field transport and mobility; piezoresistance
61.72.uj III-V and II-VI semiconductors

Controlled oxygen doping of GaN using plasma assisted molecular-beam epitaxy

A. J. Ptak, L. J. Holbert, L. Ting, C. H. Swartz, M. Moldovan, N. C. Giles, T. H. Myers, P. Van Lierde, C. Tian, R. A. Hockett, S. Mitha, A. E. Wickenden, D. D. Koleske, and R. L. Henry

Appl. Phys. Lett. 79, 2740 (2001); http://dx.doi.org/10.1063/1.1403276 (3 pages) | Cited 15 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
High-quality (0001) and (0001)-GaN films were grown by plasma-assisted molecular-beam epitaxy to study the dependence of oxygen incorporation on polarity and oxygen partial pressure. Oxygen incorporates at a rate ten times faster on nitrogen-polar GaN than on the Ga polarity. Oxygen doping is controllable, reproducible, and produces low compensation material up to concentrations of at least 1018 cm−3 with higher levels showing significant compensation. Layers containing oxygen at levels above 1022 cm−3 exhibit severe cracking while oxygen concentrations less than 1021 cm−3 do not introduce significant strain. The oxygen incorporation rate has a weak dependence on Ga overpressure during Ga-stable growth but dramatically increases for conditions approaching N-stable growth. © 2001 American Institute of Physics.
Show PACS
61.72.uj III-V and II-VI semiconductors
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
81.05.Ea III-V semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
52.77.Dq Plasma-based ion implantation and deposition
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)
73.61.Ey III-V semiconductors

Self-assembled heterojunction between electrodeposited PbS nanoparticles and indium tin oxide substrate

K. K. Nanda and S. N. Sahu

Appl. Phys. Lett. 79, 2743 (2001); http://dx.doi.org/10.1063/1.1413223 (3 pages) | Cited 15 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Self-assembled heterojunction was fabricated by means of an electrochemical deposition of PbS nanoparticles on indium tin oxide substrate. The current–voltage and capacitance–voltage studies confirmed the formation of a heterojunction. A large current and large capacitance were observed in the case of a device from particle of smaller size which is believed to be due to the large surface area contact. The rectifying behavior of the heterojunction was found to be weak as compared to the usual p–n junction. © 2001 American Institute of Physics.
Show PACS
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.40.Ei Rectification
73.63.Bd Nanocrystalline materials

Impurity-controlled dopant activation: Hydrogen-determined site selection of boron in silicon carbide

B. Aradi, P. Deák, N. T. Son, E. Janzén, W. J. Choyke, and R. P. Devaty

Appl. Phys. Lett. 79, 2746 (2001); http://dx.doi.org/10.1063/1.1410337 (3 pages) | Cited 13 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The geometry and formation energy of substitutional B and Al dopants as well as their complexes with hydrogen have been calculated in 4H–SiC using first-principles methods. Our results show that boron selecting the silicon site and, therefore, getting activated as a shallow acceptor depends on the presence of hydrogen which is promoted into the crystal by boron itself. Without hydrogen, boron would mostly be incorporated at the carbon site. Aluminum does not show this behavior: it always selects the silicon site and is incorporated independently of hydrogen. © 2001 American Institute of Physics.
Show PACS
71.55.Ht Other nonmetals
61.72.S- Impurities in crystals

Localized variations in electronic structure of AlGaN/GaN heterostructures grown by molecular-beam epitaxy

K. V. Smith, E. T. Yu, C. R. Elsass, B. Heying, and J. S. Speck

Appl. Phys. Lett. 79, 2749 (2001); http://dx.doi.org/10.1063/1.1410342 (3 pages)

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Local electronic properties in a molecular-beam-epitaxy-grown AlxGa1−xN/GaN heterostructure field-effect transistor epitaxial layer structure are probed using depth-resolved scanning capacitance microscopy. Theoretical analysis of contrast observed in scanning capacitance images acquired over a range of bias voltages is used to assess the possible structural origins of local inhomogeneities in electronic structure, which are shown to be concentrated in areas where Ga droplets had formed on the surface during growth. Within these regions, there are significant variations in the local electronic structure that are attributed to variations in both AlxGa1−xN layer thickness and Al composition. Increased charge trapping is also observed in these regions. © 2001 American Institute of Physics.
Show PACS
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
85.30.Tv Field effect devices
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
71.20.Nr Semiconductor compounds
73.20.At Surface states, band structure, electron density of states

Defect-induced lateral chemical heterogeneity at Ni/GaN interfaces and its effect on the electronic properties of the interface

A. Barinov, L. Gregoratti, B. Kaulich, M. Kiskinova, and A. Rizzi

Appl. Phys. Lett. 79, 2752 (2001); http://dx.doi.org/10.1063/1.1404411 (3 pages) | Cited 9 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Scanning photoemission microscopy (SPEM) has been used to investigate the effect of morphological defects in GaN films grown on a 6H–SiC substrate on the composition and electronic properties of Ni/GaN interfaces in the temperature range of 25–600 °C. The SPEM imaging and spectroscopy identified a direct relation between the defects and the development of spatial heterogeneity in the interfacial composition, best pronounced after moderate annealing at 300 °C. The Schottky barrier height measured at these heterogeneous interfaces changes with advancement of the Ni–GaN reaction at elevated temperatures but exhibits negligible spatial variations. © 2001 American Institute of Physics.
Show PACS
68.35.Ct Interface structure and roughness
73.20.At Surface states, band structure, electron density of states
73.40.Ns Metal-nonmetal contacts
73.30.+y Surface double layers, Schottky barriers, and work functions
61.72.Cc Kinetics of defect formation and annealing
Page 1 of 3 Pages Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close