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22 Jul 2002

Volume 81, Issue 4, pp. 571-782

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Pt Schottky contacts to n-(Ga,Mn)N

Jihyun Kim, F. Ren, G. T. Thaler, M. E. Overberg, C. R. Abernathy, S. J. Pearton, and R. G. Wilson

Appl. Phys. Lett. 81, 658 (2002); http://dx.doi.org/10.1063/1.1496130 (3 pages) | Cited 2 times

Online Publication Date: 16 July 2002

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The Schottky barrier height of Pt contacts on n-(Ga,Mn)N (n ∼ 3.5×1017 cm−3) thin films was obtained from current–voltage measurements as a function of temperature. The resulting values ranged from 0.82±0.04 eV at 25 °C to 0.79±0.06 eV at 100 °C with saturation current densities of 4.28×10−8 A cm−2 (25 °C) to 8.42×10−5 A cm−2 (100 °C), respectively. The barrier height at room temperature obtained from an activation energy plot was 0.91±0.06 eV. The reverse current magnitude was larger than predicted by thermionic emission alone, just as in n-GaN grown in a similar fashion on Al2O3 substrates. The measured barrier height for Pt on n-(Ga,Mn)N is lower than for the value reported on n-GaN(1.08 eV). © 2002 American Institute of Physics.
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73.40.Ns Metal-nonmetal contacts
73.30.+y Surface double layers, Schottky barriers, and work functions
75.50.Pp Magnetic semiconductors

Tailoring the electronic properties of GaAs/AlAs superlattices by InAs layer insertions

A. Patanè, D. Sherwood, L. Eaves, T. M. Fromhold, M. Henini, P. C. Main, and G. Hill

Appl. Phys. Lett. 81, 661 (2002); http://dx.doi.org/10.1063/1.1496140 (3 pages) | Cited 14 times

Online Publication Date: 16 July 2002

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We investigate the electrical and optical properties of GaAs/AlAs superlattices (SLs) in which a thin (⩽1.2 monolayers) InAs layer is inserted in the central plane of each GaAs quantum well. The InAs layer modifies the structure of the SL unit cell and provides an additional design parameter for tailoring the energy of the lowest miniband and the size of the minigap. We exploit this effect to enhance electron injection from a doped contact layer into the first miniband and to inhibit interminiband coupling. © 2002 American Institute of Physics.
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73.21.Cd Superlattices
73.21.Fg Quantum wells
78.67.De Quantum wells
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
81.05.Ea III-V semiconductors
68.65.Cd Superlattices
68.65.Fg Quantum wells
81.07.St Quantum wells
68.35.Ct Interface structure and roughness
73.63.Hs Quantum wells

Initial growth of GaN on α-Al2O3(0001) by molecular beam epitaxy

S. K. Davidsson, T. G. Andersson, and H. Zirath

Appl. Phys. Lett. 81, 664 (2002); http://dx.doi.org/10.1063/1.1495083 (3 pages) | Cited 5 times

Online Publication Date: 16 July 2002

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The sapphire surface, used for growth of GaN by molecular beam epitaxy, was studied by reflection high-energy electron diffraction during the in situ pretreatment and initial growth. We investigated the effect of Ga cleaning, nitridation, and growth of the AlN nucleation layer on the lattice constant. One Ga-cleaning cycle restored the surface with a higher diffraction density. Nitridation changed the lattice constant instantaneously. The lattice constant was restored if the nitridation was switched off. For the AlN nucleation layer, the first monolayer was strained, followed by first a rapid and then a slow relaxation. © 2002 American Institute of Physics.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
81.05.Ea III-V semiconductors
68.55.A- Nucleation and growth
81.65.Cf Surface cleaning, etching, patterning

Accurate modeling of direct tunneling hole current in p-metal–oxide–semiconductor devices

A. Haque and K. Alam

Appl. Phys. Lett. 81, 667 (2002); http://dx.doi.org/10.1063/1.1495084 (3 pages) | Cited 10 times

Online Publication Date: 16 July 2002

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We critically examine a number of important issues related to modeling hole direct tunneling in p-metal–oxide–semiconductor devices with p+-polycrystalline silicon gate. By comparing our simulated direct tunneling hole current with experimental data, several observations are made. It is found that inelastic trap scattering of holes in the gate-oxide region increases the hole tunneling current significantly at lower gate voltages in devices with gate-oxide thickness greater than 2 nm. Appropriate spatial and gate bias dependence of the scattering rate needs to be considered for accurately predicting experimental current over the entire gate voltage range. Effective mass of holes in gate-oxide region is not a constant, rather, it increases with increasing gate bias voltage and we propose a relationship between the two. Bulk values for hole effective masses in silicon may be used to accurately model the hole tunneling current even in the presence of hole quantization. The contribution of split-off holes to direct tunneling current is not negligible in strong inversion. © 2002 American Institute of Physics.
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73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
71.18.+y Fermi surface: calculations and measurements; effective mass, g factor
73.20.At Surface states, band structure, electron density of states

Gain dynamics and ultrafast spectral hole burning in In(Ga)As self-organized quantum dots

K. Kim, J. Urayama, T. B. Norris, J. Singh, J. Phillips, and P. Bhattacharya

Appl. Phys. Lett. 81, 670 (2002); http://dx.doi.org/10.1063/1.1493665 (3 pages) | Cited 28 times

Online Publication Date: 16 July 2002

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Using a femtosecond three-pulse pump-probe technique, we investigated spectral hole-burning and gain recovery dynamics in self-organized In(Ga)As quantum dots. The spectral hole dynamics are qualitatively different from those observed in quantum wells, and allow us to distinguish unambiguously the gain recovery due to intradot relaxation and that due to carrier capture. The gain recovery due to carrier–carrier scattering-dominated intradot relaxation is very fast ( ∼ 130 fs), indicating that this is not the factor limiting the bandwidth of directly modulated quantum dot lasers. © 2002 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
68.65.Hb Quantum dots (patterned in quantum wells)

Influence of exciton localization on the quantum efficiency of GaN/(In,Ga)N multiple quantum wells grown by molecular-beam epitaxy

S. Dhar, U. Jahn, O. Brandt, P. Waltereit, and K. H. Ploog

Appl. Phys. Lett. 81, 673 (2002); http://dx.doi.org/10.1063/1.1493237 (3 pages) | Cited 9 times

Online Publication Date: 16 July 2002

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Using cathodoluminescence spectroscopy, we investigate the dependence of the transition energy and quantum efficiency of a GaN/(In,Ga)N multiple quantum-well structure on both the temperature and excitation density. A coupled rate-equation model is introduced to explain the experimental results. Polarization field screening has been incorporated in a realistic manner by solving these coupled rate equations self-consistently along with the Schrödinger and Poisson equations. Our study suggests that exciton localization increases the internal quantum efficiency significantly. © 2002 American Institute of Physics.
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73.21.Fg Quantum wells
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
78.67.De Quantum wells
78.60.Hk Cathodoluminescence, ionoluminescence
73.20.Fz Weak or Anderson localization
71.35.Lk Collective effects (Bose effects, phase space filling, and excitonic phase transitions)

Electron energy-loss spectroscopy analysis of interface structure of yttrium oxide gate dielectrics on silicon

D. Niu, R. W. Ashcraft, Z. Chen, S. Stemmer, and G. N. Parsons

Appl. Phys. Lett. 81, 676 (2002); http://dx.doi.org/10.1063/1.1496138 (3 pages) | Cited 7 times

Online Publication Date: 16 July 2002

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Interface stability of high dielectric constant gate insulators on silicon is an important issue for advanced gate stack engineering. In this article, we analyze the silicon/dielectric interface structure for thin Y2O3 and Y silicate films deposited by chemical vapor deposition on clean and prenitrided Si(100) using high-resolution transmission electron microscopy, electron energy-loss spectroscopy, and x-ray photoelectron spectroscopy. The analysis shows the films to be stoichiometric Y2O3 on top and Y-silicate/SiO2 at the dielectric/Si interface. Prenitridation of the silicon surface impedes the reaction between the depositing film and the substrate, promoting a Si-free Y2O3 structure. Possible mechanisms leading to the observed Y2O3 and Y silicate structures are discussed. © 2002 American Institute of Physics.
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68.35.Ct Interface structure and roughness
81.65.Lp Surface hardening: nitridation, carburization, carbonitridation
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
81.05.Cy Elemental semiconductors
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
68.55.-a Thin film structure and morphology
79.20.Uv Electron energy loss spectroscopy
68.37.Lp Transmission electron microscopy (TEM)
77.55.-g Dielectric thin films
77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.

Transient carrier velocities in bulk GaAs: Quantitative comparison between terahertz data and ensemble Monte Carlo calculations

M. Abe, S. Madhavi, Y. Shimada, Y. Otsuka, K. Hirakawa, and K. Tomizawa

Appl. Phys. Lett. 81, 679 (2002); http://dx.doi.org/10.1063/1.1495540 (3 pages) | Cited 14 times

Online Publication Date: 16 July 2002

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Transient carrier velocities determined from terahertz radiation emitted from photoexcited bulk GaAs have been compared with ensemble Monte Carlo calculations. It is found that, if actual experimental conditions (sample geometry, photoexcitation condition, etc.) are properly taken into account, Monte Carlo calculations give a very good description of the transient carrier velocities determined from THz measurements. Although the THz signal is dominated by electron transport, contribution of holes becomes appreciable when the electric field is higher than 20 kV/cm. © 2002 American Institute of Physics.
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72.20.Ht High-field and nonlinear effects
72.80.Ey III-V and II-VI semiconductors
81.05.Ea III-V semiconductors
72.40.+w Photoconduction and photovoltaic effects
78.55.Cr III-V semiconductors
72.20.Dp General theory, scattering mechanisms
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