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2 Dec 2002

Volume 81, Issue 23, pp. 4315-4476

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Biaxial strain-modified valence and conduction band offsets of zinc-blende GaN, GaP, GaAs, InN, InP, and InAs, and optical bowing of strained epitaxial InGaN alloys

P. R. C. Kent, Gus L. W. Hart, and Alex Zunger

Appl. Phys. Lett. 81, 4377 (2002); http://dx.doi.org/10.1063/1.1524299 (3 pages) | Cited 18 times

Online Publication Date: 25 November 2002

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Using density-functional calculations, we obtain the (001) biaxial strain dependence of the valence and conduction band energies of GaN, GaP, GaAs, InN, InP, and InAs. The results are fit to a convenient-to-use polynomial and the fits provided in tabular form. Using the calculated biaxial deformation potentials in large supercell empirical pseudopotential calculations, we demonstrate that epitaxial strain reduces the InGaN alloy bowing coefficient compared to relaxed bulk alloys. © 2002 American Institute of Physics.
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71.20.Nr Semiconductor compounds
71.15.Dx Computational methodology (Brillouin zone sampling, iterative diagonalization, pseudopotential construction)
71.15.Mb Density functional theory, local density approximation, gradient and other corrections

Size effects on generation-recombination noise

G. Gomila and L. Reggiani

Appl. Phys. Lett. 81, 4380 (2002); http://dx.doi.org/10.1063/1.1526915 (3 pages) | Cited 7 times

Online Publication Date: 25 November 2002

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We carry out an analytical theory of generation-recombination noise for a two-level resistor model which goes beyond those presently available by including the effects of both space charge fluctuations and diffusion current. Finite size effects are found responsible for the saturation of the low frequency current spectral density at high enough applied voltages. The saturation behavior is controlled essentially by the correlations coming from the long range Coulomb interaction. It is suggested that the saturation of the current fluctuations for high voltage bias constitutes a general feature of generation-recombination noise. © 2002 American Institute of Physics.
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72.70.+m Noise processes and phenomena
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
73.40.Ns Metal-nonmetal contacts
72.30.+q High-frequency effects; plasma effects
72.20.Ht High-field and nonlinear effects

Polymer thin-film transistors with chemically modified dielectric interfaces

A. Salleo, M. L. Chabinyc, M. S. Yang, and R. A. Street

Appl. Phys. Lett. 81, 4383 (2002); http://dx.doi.org/10.1063/1.1527691 (3 pages) | Cited 171 times

Online Publication Date: 25 November 2002

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The characteristics of polymeric thin-film transistors can be controlled by chemically modifying the surface of the gate dielectric prior to the deposition of the organic semiconductor. The chemical treatment consists of derivatizing the silicon oxide surface with organic trichlorosilanes to form self-assembled monolayers (SAMs). The deposition of an octadecyltrichlorosilane SAM leads to a mobility of 0.01–0.02 cm2/V s in a polyfluorene copolymer, a 20-fold improvement over the mobility on bare silicon oxide. The mobility enhancement mechanism is likely to involve molecular interactions between the polymer and the SAM. © 2002 American Institute of Physics.
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81.65.-b Surface treatments
81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials
85.30.Tv Field effect devices
72.80.Le Polymers; organic compounds (including organic semiconductors)
73.61.Ph Polymers; organic compounds
73.50.Dn Low-field transport and mobility; piezoresistance
72.20.Fr Low-field transport and mobility; piezoresistance
68.47.Pe Langmuir-Blodgett films on solids; polymers on surfaces; biological molecules on surfaces

Interfacial properties of single-crystalline CeO2 high-k gate dielectrics directly grown on Si (111)

Yukie Nishikawa, Takeshi Yamaguchi, Masahiko Yoshiki, Hideki Satake, and Noburu Fukushima

Appl. Phys. Lett. 81, 4386 (2002); http://dx.doi.org/10.1063/1.1526169 (3 pages) | Cited 33 times

Online Publication Date: 25 November 2002

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Interfacial properties of single-crystalline CeO2 high-k dielectrics directly grown on Si (111) were investigated by comparing metal–insulator–semiconductor field-effect transistors (MISFETs) without any interfacial layer [(w/o-IL); direct growth of CeO2 on Si] and those with an interfacial layer (w-IL). FET characteristics, such as the drain current and the S factor, for the w/o-IL MISFET were much worse than those for the w-IL MISFET. The in-gap states attributed to the oxygen defects were detected in the CeO2 directly grown on Si by x-ray photoelectron spectroscopy measurements. The large interface state density induced by the oxygen defects at the CeO2/Si interface may deteriorate the w/o-IL MISFET performances. © 2002 American Institute of Physics.
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73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
85.30.Tv Field effect devices
73.20.Hb Impurity and defect levels; energy states of adsorbed species
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

Comparative study on the broadening of exciton luminescence linewidth due to phonon in zinc-blende and wurtzite GaN epilayers

S. J. Xu, L. X. Zheng, S. H. Cheung, M. H. Xie, S. Y. Tong, and Hui Yang

Appl. Phys. Lett. 81, 4389 (2002); http://dx.doi.org/10.1063/1.1526450 (3 pages) | Cited 8 times

Online Publication Date: 25 November 2002

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Linewidth broadening of exciton luminescence in wurtzite and zinc-blende GaN epilayers was investigated as a function of temperature with photoluminescence. A widely accepted theoretical model was used to fit the experimental data, so that the coupling parameters between exciton and acoustic and longitudinal optical phonons were obtained for both structures. It was found that the coupling constants of both exciton–acoustic optical phonon coupling and exciton–longitudinal optical phonon coupling for zinc-blende GaN are almost twice as much as the corresponding values of wurtzite GaN. These results show that the relatively strong exciton–phonon scattering seems to be characteristic to zinc-blende GaN film. © 2002 American Institute of Physics.
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78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
71.35.Gg Exciton-mediated interactions
63.20.kk Phonon interactions with other quasiparticles

Pulsed atomic-layer epitaxy of ultrahigh-quality AlxGa1−xN structures for deep ultraviolet emissions below 230 nm

J. P. Zhang, M. Asif Khan, W. H. Sun, H. M. Wang, C. Q. Chen, Q. Fareed, E. Kuokstis, and J. W. Yang

Appl. Phys. Lett. 81, 4392 (2002); http://dx.doi.org/10.1063/1.1528726 (3 pages) | Cited 54 times

Online Publication Date: 25 November 2002

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In this letter, we report the pulsed atomic-layer epitaxy of ultrahigh-quality AlN epilayers and AlN/Al0.85Ga0.15N multiple quantum wells (MQWs) on basal plane sapphire substrates. Symmetric and asymmetric x-ray diffraction (XRD) measurements and room-temperature (RT) photoluminescence (PL) were used to establish the ultrahigh structural and optical quality. Strong band-edge RT PL at 208 and 228 nm was obtained from the AlN epilayers and the AlN/Al0.85Ga0.15N MQWs. These data clearly establish their suitability for sub-250-nm deep UV emitters. © 2002 American Institute of Physics.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
78.67.De Quantum wells
78.55.Cr III-V semiconductors
81.07.St Quantum wells
68.65.Fg Quantum wells
81.05.Ea III-V semiconductors

Realization of wide electron slabs by polarization bulk doping in graded III–V nitride semiconductor alloys

Debdeep Jena, Sten Heikman, Daniel Green, Dario Buttari, Robert Coffie, Huili Xing, Stacia Keller, Steve DenBaars, James S. Speck, Umesh K. Mishra, and Ioulia Smorchkova

Appl. Phys. Lett. 81, 4395 (2002); http://dx.doi.org/10.1063/1.1526161 (3 pages) | Cited 21 times

Online Publication Date: 25 November 2002

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We present the concept and experimental realization of polarization-induced bulk electron doping in III–V nitride semiconductors. By exploiting the large polarization charges in the III–V nitrides, we are able to create wide slabs of high-density mobile electrons without introducing shallow donors. Transport measurements reveal the superior properties of the polarization-doped electron distributions than comparable shallow donor-doped structures, especially at low temperatures due to the removal of ionized impurity scattering. Such polarization-induced three-dimensional electron slabs can be utilized in a variety of device structures owing to their high conductivity and continuously changing energy gap. © 2002 American Institute of Physics.
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73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
61.72.uj III-V and II-VI semiconductors
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)
73.50.Dn Low-field transport and mobility; piezoresistance
71.55.Eq III-V semiconductors
73.20.Hb Impurity and defect levels; energy states of adsorbed species
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