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12 Mar 2001

Volume 78, Issue 11, pp. 1463-1639

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Electrophoresis deposition of carbon nanotubes for triode-type field emission display

W. B. Choi, Y. W. Jin, H. Y. Kim, S. J. Lee, M. J. Yun, J. H. Kang, Y. S. Choi, N. S. Park, N. S. Lee, and J. M. Kim

Appl. Phys. Lett. 78, 1547 (2001); http://dx.doi.org/10.1063/1.1349870 (3 pages) | Cited 103 times

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A triode-type field emission display has been fabricated using carbon nanotube emitters. Purified single walled carbon nanotubes were selectively deposited onto a cathode electrode in a triode-type structure by an electrophoresis. Emission current was modulated with gate potentials of 100–300 V. A high brightness of 1000 cd/m2 with uniform emission was obtained at 900 V at the anode and 200 V at the gate. The fluctuation of emission current was found to be less than 5% in a fully sealed field emission display. Selective deposition of carbon nanotubes by electrophoresis shows high feasibility for triode-type field emission displays. © 2001 American Institute of Physics.
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81.07.De Nanotubes
85.35.Kt Nanotube devices
85.45.Fd Field emission displays (FEDs)
61.46.-w Structure of nanoscale materials
61.48.-c Structure of fullerenes and related hollow and planar molecular structures
81.05.ub Fullerenes and related materials
82.45.Qr Electrodeposition and electrodissolution

Limits on the Curie temperature of (III,Mn)V ferromagnetic semiconductors

John Schliemann, Jürgen König, Hsiu-Hau Lin, and Allan H. MacDonald

Appl. Phys. Lett. 78, 1550 (2001); http://dx.doi.org/10.1063/1.1355300 (3 pages) | Cited 57 times

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Mean-field-theory predicts that the Curie temperature Tc of a (III,Mn)V ferromagnet will be proportional to the valence band density-of-states of its host (III,V) semiconductor, suggesting a route toward room-temperature ferromagnetism in this materials class. In this letter, we use theoretical estimates of spin-wave energies and Monte Carlo simulations to demonstrate that long-wavelength collective fluctuations, neglected by mean-field theory, will limit the critical temperature in large density-of-states materials. We discuss implications for high Tc searches. © 2001 American Institute of Physics.
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75.50.Pp Magnetic semiconductors
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
75.50.Dd Nonmetallic ferromagnetic materials
75.40.Mg Numerical simulation studies
75.30.Ds Spin waves
75.40.Gb Dynamic properties (dynamic susceptibility, spin waves, spin diffusion, dynamic scaling, etc.)
71.20.Nr Semiconductor compounds
75.30.Cr Saturation moments and magnetic susceptibilities
75.30.Et Exchange and superexchange interactions

Photovoltaic effects on pinch-off voltage and open-circuit voltage in high-electron-mobility-transistor and Schottky-diode configurations

D. M. Kim

Appl. Phys. Lett. 78, 1553 (2001); http://dx.doi.org/10.1063/1.1355295 (3 pages)

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Photovoltaic effects on the pinch-off voltage (VP) in the high-electron-mobility-transistor (HEMT) and the open-circuit photovoltage (Vopt,OC) in the Schottky-diode configurations are characterized as a function of the optical input (Popt). The open-circuit photovoltage (Vopt,OC) in a Schottky-diode configuration, which has only a vertical field and every photogenerated excess minority carrier contributes to the photovoltage, can be described by Vopt,OC = nVth ln(Popt/Pref). However, the photovoltage (Vopt,FET ≡ ∣VP-VPO∣) in HEMT configuration, which has a lateral field as well as a vertical field to drift excess minority carriers to the source contact and results in reduced photovoltage development, can be modeled as Vopt,FET = V0(Popt/Prefo)γ. © 2001 American Institute of Physics.
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85.30.Tv Field effect devices
85.60.Bt Optoelectronic device characterization, design, and modeling
85.30.Kk Junction diodes
73.50.Pz Photoconduction and photovoltaic effects
85.30.De Semiconductor-device characterization, design, and modeling

Polarization-dependent discharge in fibers of a semiconducting ladder-type polymer

N. Kumar and K. S. Narayan

Appl. Phys. Lett. 78, 1556 (2001); http://dx.doi.org/10.1063/1.1354159 (3 pages) | Cited 4 times

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We report results on polarization-dependent photoinduced discharge in oriented fibers and films of ladder-type, electron-transporting polymer poly(benzimidazobenzophenanthroline). The photocarrier generation efficiency (ϕ) in the fiber, which is indicated by the rate of discharge, is found to be distinctly higher for light polarized parallel to the fiber axis (P∥) compared to the radially perpendicular direction (P⊥). Similar results, with ϕ anisotropy ∼ 10, are obtained for oriented films. These observations are different from previously obtained results on polyparaphenylenevinylene. The results are compared with polarization-dependent steady-state photoconductivity measurements. We interpret these results on the basis of molecular and macroscopic features of the material. © 2001 American Institute of Physics.
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72.40.+w Photoconduction and photovoltaic effects
61.41.+e Polymers, elastomers, and plastics
78.60.Fi Electroluminescence
73.61.Ph Polymers; organic compounds
73.50.Pz Photoconduction and photovoltaic effects
78.66.Qn Polymers; organic compounds

Photoluminescence modulation by high-frequency lateral electric fields in quantum wells

S. K. Zhang, P. V. Santos, and R. Hey

Appl. Phys. Lett. 78, 1559 (2001); http://dx.doi.org/10.1063/1.1355292 (3 pages) | Cited 3 times

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We investigate the modulation of the excitonic photoluminescence (PL) of GaAs quantum wells by high-frequency (frf) lateral electric fields. Under these fields, the PL becomes modulated in the form of pulses with repetition frequency of 2 frf. The periodic PL modulation is attributed to the time-dependent ionization of photogenerated excitons under the lateral electric field. The exciton ionization mechanism is proposed to be the impact ionization with electrons accelerated by the electric fields with a threshold field for ionization of about 15 V/cm. The different transport properties of electrons and holes are found to play a role in the exciton ionization process. © 2001 American Institute of Physics.
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78.67.De Quantum wells
73.21.Fg Quantum wells
78.20.Jq Electro-optical effects
78.55.Cr III-V semiconductors
73.63.Hs Quantum wells
73.50.Mx High-frequency effects; plasma effects
71.35.Gg Exciton-mediated interactions
78.47.-p Spectroscopy of solid state dynamics

On the origin of carrier localization in Ga1−xInxNyAs1−y/GaAs quantum wells

M.-A. Pinault and E. Tournié

Appl. Phys. Lett. 78, 1562 (2001); http://dx.doi.org/10.1063/1.1354153 (3 pages) | Cited 72 times

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We have investigated by temperature-dependent photoluminescence (PL) spectroscopy as-grown GaInNAs, InGaAs, and GaAsN quantum wells (QWs) embedded in a GaAs matrix. The evolution of the PL peak position and of the PL linewidth shows evidence of a strong carrier localization for the GaInNAs QWs only. The high delocalization temperature, in the 150 K range, indicates the presence of a high density of possibly deep-localizing potential wells. In addition, a higher density of nonradiative recombination centers appears to result in stronger carrier localization. Transmission electron microscopy reveals well defined, flat interfaces, in these comparatively high N-content (yN ∼ 0.04–0.05) QWs. Our results thus demonstrate that the origin of localization in GaInNAs QWs is the concomitant presence of both In and N, which may result in strain and/or composition fluctuations. © 2001 American Institute of Physics.
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73.21.Fg Quantum wells
68.65.Fg Quantum wells
78.67.De Quantum wells
78.55.Cr III-V semiconductors
73.20.Jc Delocalization processes

Large-scale local-density-approximation band gap-corrected GaAsN calculations

Lin-Wang Wang

Appl. Phys. Lett. 78, 1565 (2001); http://dx.doi.org/10.1063/1.1354162 (3 pages) | Cited 38 times

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The electronic structure of a GaAsN alloy is calculated using a 4096 atom supercell, with a 70 Ry plane wave basis cutoff and Ga atom 3d electrons as valence electrons. The charge density of this supercell is generated by patching the charge density of a small unit cell with the charge density of bulk GaAs. The local-density-approximation band gap error is corrected by modifying the nonlocal pseudopotentials. A localized nitrogen state [a1(N)] is obtained,and it plays an important role in the band gap reduction of GaAsN. © 2001 American Institute of Physics.
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71.20.Nr Semiconductor compounds
71.15.Mb Density functional theory, local density approximation, gradient and other corrections
71.15.Dx Computational methodology (Brillouin zone sampling, iterative diagonalization, pseudopotential construction)

Auger recombination in long-wavelength infrared InNxSb1−x alloys

B. N. Murdin, M. Kamal-Saadi, A. Lindsay, E. P. O’Reilly, A. R. Adams, G. J. Nott, J. G. Crowder, C. R. Pidgeon, I. V. Bradley, J.-P. R. Wells, T. Burke, A. D. Johnson, and T. Ashley

Appl. Phys. Lett. 78, 1568 (2001); http://dx.doi.org/10.1063/1.1355301 (3 pages) | Cited 26 times

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Dilute nitrogen alloys of InSb exhibit strong band gap bowing with increasing nitrogen composition, shifting the absorption edge to longer wavelengths. The conduction band dispersion also has an enhanced nonparabolicity, which suppresses Auger recombination. We have measured Auger lifetimes in alloys with 11 and 15 μm absorption edges using a time-resolved pump-probe technique. We find the lifetimes to be longer at room temperature than equivalent band gap Hg1−yCdyTe alloys at the same quasi-Fermi level separation. The results are explained using a modified k⋅p Hamiltonian which explicitly includes interactions between the conduction band and a higher lying nitrogen-related resonant band. © 2001 American Institute of Physics.
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78.30.Fs III-V and II-VI semiconductors
78.47.-p Spectroscopy of solid state dynamics
71.20.Nr Semiconductor compounds

Hydrogen passivation and activation of oxygen complexes in silicon

S. N. Rashkeev, M. Di Ventra, and S. T. Pantelides

Appl. Phys. Lett. 78, 1571 (2001); http://dx.doi.org/10.1063/1.1355297 (3 pages) | Cited 10 times

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We report first-principles calculations in terms of which we describe the role of hydrogen in passivating or activating oxygen complexes in Si. In particular we find that attaching H to a pre-existing oxygen cluster can change the electric activity of the cluster. Furthermore, the addition of a hydrogen atom in the core structure of thermal donors can account for the NL10 electron-paramagnetic-resonance signal. The interaction of H with the thermal-donor-like defects at the Si–SiO2 is also discussed. © 2001 American Institute of Physics.
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71.55.Cn Elemental semiconductors
71.15.Mb Density functional theory, local density approximation, gradient and other corrections
76.30.Mi Color centers and other defects
73.20.Hb Impurity and defect levels; energy states of adsorbed species

Band discontinuities in ZnMgSe/ZnCdSe(001) lattice-matched heterostructures

E. Pelucchi, S. Rubini, B. Bonanni, A. Franciosi, and M. Peressi

Appl. Phys. Lett. 78, 1574 (2001); http://dx.doi.org/10.1063/1.1350968 (3 pages) | Cited 2 times

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We present experimental and theoretical studies of lattice-matched interfaces between Zn1−yMgySe and Zn1−xCdxSe wide-band gap semiconductors. Ab initio pseudopotential calculations predict lattice matching for y/x∼1.6 and a valence band contribution to the band gap difference Qv decreasing gradually from 0.34 to 0.27 with increasing x and y. Experimental x-ray diffraction and photoemission spectroscopy results are mostly consistent with such predictions, although non-negligible deviations of the band offsets from commutativity were observed for selected alloy compositions. © 2001 American Institute of Physics.
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73.20.At Surface states, band structure, electron density of states
79.60.Jv Interfaces; heterostructures; nanostructures
71.15.Dx Computational methodology (Brillouin zone sampling, iterative diagonalization, pseudopotential construction)

n- and p-type dopants for cubic silicon nitride

Fumiyasu Oba, Kazuyoshi Tatsumi, Hirohiko Adachi, and Isao Tanaka

Appl. Phys. Lett. 78, 1577 (2001); http://dx.doi.org/10.1063/1.1354667 (3 pages) | Cited 8 times

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The formation and ionization energies of impurities in cubic silicon nitride are investigated through first-principles calculations. Among the elements in the groups III to VI, P and O are preferable for n-type doping, while Al is favorable for p-type doping in terms of the formation and ionization energies. The compensation of doped carriers associated with the incorporation of these impurities into anti and interstitial sites can be suppressed if appropriate growth conditions are chosen. © 2001 American Institute of Physics.
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61.72.up Other materials
71.15.Nc Total energy and cohesive energy calculations
71.55.Ht Other nonmetals
61.72.J- Point defects and defect clusters

SiGeC/Si superlattice microcoolers

Xiaofeng Fan, Gehong Zeng, Chris LaBounty, John E. Bowers, Edward Croke, Channing C. Ahn, Scott Huxtable, Arun Majumdar, and Ali Shakouri

Appl. Phys. Lett. 78, 1580 (2001); http://dx.doi.org/10.1063/1.1356455 (3 pages) | Cited 81 times

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Monolithically integrated active cooling is an attractive way for thermal management and temperature stabilization of microelectronic and optoelectronic devices. SiGeC can be lattice matched to Si and is a promising material for integrated coolers. SiGeC/Si superlattice structures were grown on Si substrates by molecular beam epitaxy. Thermal conductivity was measured by the 3ω method. SiGeC/Si superlattice microcoolers with dimensions as small as 40×40 μm2 were fabricated and characterized. Cooling by as much as 2.8 and 6.9 K was measured at 25 °C and 100 °C, respectively, corresponding to maximum spot cooling power densities on the order of 1000 W/cm2. © 2001 American Institute of Physics.
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07.20.-n Thermal instruments and apparatus
68.65.Cd Superlattices
66.70.-f Nonelectronic thermal conduction and heat-pulse propagation in solids; thermal waves
85.80.Fi Thermoelectric devices
85.40.-e Microelectronics: LSI, VLSI, ULSI; integrated circuit fabrication technology
68.60.Dv Thermal stability; thermal effects
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
81.07.-b Nanoscale materials and structures: fabrication and characterization

Bipolarity in electrical conduction of transparent oxide semiconductor CuInO2 with delafossite structure

Hiroshi Yanagi, Tomomi Hase, Shuntaro Ibuki, Kazushige Ueda, and Hideo Hosono

Appl. Phys. Lett. 78, 1583 (2001); http://dx.doi.org/10.1063/1.1355673 (3 pages) | Cited 105 times

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A transparent oxide semiconductor with delafossite structure, CuInO2, was found to exhibit both p-type and n-type conduction by doping of an appropriate impurity and tuning of proper film-deposition conditions. Thin films of Ca-doped or Sn-doped CuInO2 (optical band gap = ∼ 3.9 eV) were prepared on α-Al2O3(001) single crystal substrates by pulsed laser deposition method. The films were deposited at 723 K in O2 atmosphere of 1.0 Pa for the Ca-doped films or 1.5 Pa for the Sn-doped films. The positive sign of the Seebeck coefficient demonstrated p-type conduction in the Ca-doped films, while the Seebeck coefficient of the Sn-doped films was negative indicating n-type conductivity. The electrical conductivities of Ca-doped and Sn-doped CuInO2 thin films were 2.8×10−3 S cm−1 and 3.8×10−3 S cm−1, respectively, at 300 K. © 2001 American Institute of Physics.
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73.61.Le Other inorganic semiconductors
73.50.Lw Thermoelectric effects
68.55.-a Thin film structure and morphology
81.15.Fg Pulsed laser ablation deposition
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