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11 Aug 2008

Volume 93, Issue 6, Articles (06xxxx)

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Appl. Phys. Lett. 93, 062101 (2008); http://dx.doi.org/10.1063/1.2968206 (3 pages)

K. Shibata and K. Hirakawa
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High Kondo temperature (TK ∼ 80 K) in self-assembled InAs quantum dots laterally coupled to nanogap electrodes

K. Shibata and K. Hirakawa

Appl. Phys. Lett. 93, 062101 (2008); http://dx.doi.org/10.1063/1.2968206 (3 pages) | Cited 7 times

Online Publication Date: 11 August 2008

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We have fabricated single electron tunneling structures by forming nanogap metallic electrodes directly upon single self-assembled InAs quantum dots (QDs). The fabricated samples exhibited clear Coulomb blockade effects. Furthermore, a clear Kondo effect was observed when strong coupling between the electrodes and the QDs was realized using a large QD with a diameter of ∼ 100 nm. From the temperature dependence of the linear conductance at the Kondo valley, the Kondo temperature TK was determined to be ∼ 81 K. This is the highest TK ever reported for artificial quantum nanostructures.
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73.40.Ns Metal-nonmetal contacts
73.23.Hk Coulomb blockade; single-electron tunneling
72.15.Qm Scattering mechanisms and Kondo effect
73.63.Kv Quantum dots

Investigation of local electrical properties of coincidence-site-lattice boundaries in location-controlled silicon islands using scanning capacitance microscopy

Nobuyuki Matsuki, Ryoichi Ishihara, Alessando Baiano, and Kees Beenakker

Appl. Phys. Lett. 93, 062102 (2008); http://dx.doi.org/10.1063/1.2968663 (3 pages) | Cited 10 times

Online Publication Date: 11 August 2008

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We used scanning capacitance microscopy (SCM) to investigate the electrical activity of grain boundaries consisting of random and coincidence-site-lattice (CSL) boundaries in location-controlled silicon islands, which were fabricated using the μ-Czochralski process with an excimer laser. The SCM results suggest that the electrical activity of the {122}∑9 CSL boundary is much smaller than that of a random boundary, and the {111}∑3 CSL boundary is negligible. This is consistent with previous theoretical predictions and experimental results for thin-film transistors.
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73.61.Cw Elemental semiconductors
61.72.Mm Grain and twin boundaries
81.10.Fq Growth from melts; zone melting and refining

The use of doping spikes in GaN Gunn diodes

R. F. Macpherson and G. M. Dunn

Appl. Phys. Lett. 93, 062103 (2008); http://dx.doi.org/10.1063/1.2969779 (2 pages) | Cited 5 times

Online Publication Date: 11 August 2008

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The possibility of circumventing the difficulties of fine doping control in GaN Gunn diode devices by the substitution of a fully depleted p-type doping spike for the doping notch used to promote domain formation is explored using a Monte Carlo model. The p-type doping spike is a commonly used structure, but its potential use in GaN has not been previously evaluated. The results for a functional doping spike are compared, favorably, to those for a physically reasonable doping notch.
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84.40.Dc Microwave circuits
85.30.Fg Bulk semiconductor and conductivity oscillation devices (including Hall effect devices, space-charge-limited devices, and Gunn effect devices)
02.70.Uu Applications of Monte Carlo methods
61.72.uj III-V and II-VI semiconductors

Driving Weiss oscillations to zero resistance states by microwave Radiation

J. Iñarrea and G. Platero

Appl. Phys. Lett. 93, 062104 (2008); http://dx.doi.org/10.1063/1.2969796 (3 pages) | Cited 8 times

Online Publication Date: 11 August 2008

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We present a theoretical model to study the effect of microwave radiation on Weiss oscillations. In our proposal Weiss oscillations, produced by a spatial periodic potential, are modulated by microwave radiation due to an interference effect between both, space and time-dependent, potentials. The final magnetoresistance depends mainly on the spatial period of the spatial potential and the frequency of radiation. Depending on the values of these parameters, we predict that Weiss oscillations can reach zero resistance states. On the other hand, these dissipationless transport states, created just by radiation, can be destroyed by the presence of a space-dependent potential.
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61.80.-x Physical radiation effects, radiation damage
73.21.Cd Superlattices
73.43.Qt Magnetoresistance

Modified permittivity observed in bulk gallium arsenide and gallium phosphide samples at 50 K using the whispering gallery mode method

John G. Hartnett, David Mouneyrac, Jean-Michel Le Floch, Jerzy Krupka, Michael E. Tobar, and D. Cros

Appl. Phys. Lett. 93, 062105 (2008); http://dx.doi.org/10.1063/1.2969905 (3 pages) | Cited 4 times

Online Publication Date: 11 August 2008

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Whispering gallery modes in bulk cylindrical gallium arsenide and gallium phosphide samples have been examined both in darkness and under white light at 50 K. In both samples we observed change in permittivity under light and dark conditions. This results from a change in the polarization state of the semiconductor, which is consistent with a free electron-hole creation/recombination process. The permittivity of the semiconductor is modified by free photocarriers in the surface layers of the sample which is the region sampled by whispering gallery modes.
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77.22.Ch Permittivity (dielectric function)
72.80.Ey III-V and II-VI semiconductors
77.22.Ej Polarization and depolarization
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
72.40.+w Photoconduction and photovoltaic effects

Resonant tunneling through double-bended graphene nanoribbons

Z. Z. Zhang, Kai Chang, and K. S. Chan

Appl. Phys. Lett. 93, 062106 (2008); http://dx.doi.org/10.1063/1.2970957 (3 pages) | Cited 16 times

Online Publication Date: 12 August 2008

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We investigate theoretically resonant tunneling through double-bended graphene nanoribbon (GNR) structures, i.e., armchair-edged GNRs (AGNRs) in between two semi-infinite zigzag GNR leads. Our numerical results demonstrate that the resonant tunneling can be tuned dramatically by the Fermi energy and the length and/or widths of the AGNR for both the metallic and semiconductorlike AGNRs. The structure can also be use to control the valley polarization of the tunneling currents and could be useful for potential application in valleytronics devices.
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73.40.Gk Tunneling
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
73.22.-f Electronic structure of nanoscale materials and related systems

Study on interfacial properties of InGaAs and GaAs integrated with chemical-vapor-deposited high-k gate dielectrics using x-ray photoelectron spectroscopy

H. J. Oh, J. Q. Lin, S. J. Lee, G. K. Dalapati, A. Sridhara, D. Z. Chi, S. J. Chua, G. Q. Lo, and D. L. Kwong

Appl. Phys. Lett. 93, 062107 (2008); http://dx.doi.org/10.1063/1.2968293 (3 pages) | Cited 7 times

Online Publication Date: 14 August 2008

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Interfacial reaction study using x-ray photoelectron spectroscopy was carried out for metal-organic chemical-vapor-deposited HfO2 and HfAlO gate dielectrics on p-In0.53Ga0.47As layer as compared to the cases of p-GaAs substrate. The results show that the alloying of GaAs with InAs (In0.53Ga0.47As) in the III-V channel layer and the alloying HfO2 with Al2O3 in the high-k dielectric can be an effective way to improve the interface quality due to their significant suppression effects on native oxides formation, especially arsenic oxide which causes Fermi level pinning on the high-k/III-V channel interface during the fabrication processes. Transmission electron microscopy result and the electrical characteristics of HfAlO/p-In0.53Ga0.47As capacitors further validate the x-ray photoelectron spectroscopy observations.
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68.55.ag Semiconductors
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
79.60.Jv Interfaces; heterostructures; nanostructures
77.55.-g Dielectric thin films
71.20.Nr Semiconductor compounds

Stability of B–H and B–D complexes in diamond under electron beam excitation

J. Barjon, A. Mehdaoui, F. Jomard, J. Chevallier, C. Mer, M. Nesladek, P. Bergonzo, J. Pernot, F. Omnès, and A. Deneuville

Appl. Phys. Lett. 93, 062108 (2008); http://dx.doi.org/10.1063/1.2965115 (3 pages) | Cited 8 times

Online Publication Date: 14 August 2008

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The substitution of hydrogen by deuterium is generally known to increase the stability of the defect passivation in semiconductors, occasionally giving rise to giant isotope effects. In this work, the stability under an electron beam irradiation of boron-hydrogen and boron-deuterium pairs in diamond are compared. The dissociation kinetics was followed in situ by cathodoluminescence spectroscopy. Surprisingly, B–H complexes are more stable than B–D complexes under electron beam at low temperature ( ∼ 100 K), with a dissociation rate about twice smaller. These experimental results are coherent with a dissociation mechanism involving a cumulative vibrational excitation of the complexes.
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68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
81.65.Rv Passivation
82.30.Lp Decomposition reactions (pyrolysis, dissociation, and fragmentation)
61.82.Fk Semiconductors
78.66.Db Elemental semiconductors and insulators
78.60.Hk Cathodoluminescence, ionoluminescence

Separation of bulk and surface electron transport in metamorphic InAs layers using quantitative mobility spectrum analysis

Y. Lin, A. R. Arehart, A. M. Carlin, and S. A. Ringel

Appl. Phys. Lett. 93, 062109 (2008); http://dx.doi.org/10.1063/1.2970045 (3 pages) | Cited 4 times

Online Publication Date: 14 August 2008

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Electron transport in low dislocation density, strain-relaxed InAs layers grown on metamorphic InAsyP1−y/InP substrates by molecular beam epitaxy was characterized using quantitative mobility spectrum analysis (QMSA) of Hall effect measurements. QMSA applied to systematically varied metamorphic InAs samples reveals high bulk electron mobilities of ∼ 20 000 cm2/V s at 300 K at a Si doping concentration of 1×1017 cm−3, simultaneously with a separate population of much slower electrons having an average mobility of ∼ 2400 cm2/V s due to parallel conduction within the InAs surface electron accumulation layer. Measurements made on higher doped samples reveal only a single electron population participating in transport due to lowered surface band bending that reduces surface accumulation of electrons in conjunction with the high conductivity of the high mobility metamorphic InAs bulk that overwhelms any remaining surface conductivity in the Hall effect measurements.
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73.61.Ey III-V semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
73.25.+i Surface conductivity and carrier phenomena
61.72.U- Doping and impurity implantation
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)
68.55.ag Semiconductors

High thermoelectric efficiency in lanthanum doped Yb14MnSb11

Eric S. Toberer, Shawna R. Brown, Teruyuki Ikeda, Susan M. Kauzlarich, and G. Jeffrey Snyder

Appl. Phys. Lett. 93, 062110 (2008); http://dx.doi.org/10.1063/1.2970089 (3 pages) | Cited 25 times

Online Publication Date: 15 August 2008

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Lanthanum doping of the high-temperature p-type thermoelectric material Yb14MnSb11 enhances the figure of merit (zT) through carrier concentration tuning. This is achieved by substituting La3+ on the Yb2+ site to reduce the free hole concentration as expected from the change in valence. The high-temperature transport properties (Seebeck coefficient, electrical resistivity, Hall mobility, and thermal conductivity) of Yb13.6La0.4MnSb11 are explained by the change in carrier concentration using a simple rigid parabolic band model, similar to that found in Yb14Mn1−xAlxSb11. Together, use of these two dopant sites enables the partial decoupling of electronic and structural properties in Yb14MnSb11-based materials.
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72.15.Jf Thermoelectric and thermomagnetic effects
61.72.up Other materials
61.66.Dk Alloys
72.15.Gd Galvanomagnetic and other magnetotransport effects
72.15.Eb Electrical and thermal conduction in crystalline metals and alloys

A study of metal-oxide-semiconductor capacitors on GaAs, In0.53Ga0.47As, InAs, and InSb substrates using a germanium interfacial passivation layer

Hyoung-Sub Kim, I. Ok, M. Zhang, F. Zhu, S. Park, J. Yum, H. Zhao, Jack C. Lee, Prashant Majhi, N. Goel, W. Tsai, C. K. Gaspe, and M. B. Santos

Appl. Phys. Lett. 93, 062111 (2008); http://dx.doi.org/10.1063/1.2972107 (3 pages) | Cited 11 times

Online Publication Date: 15 August 2008

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In this letter, we present electrical characteristics of HfO2-based metal-oxide-semiconductor capacitors (MOSCAPs) on n- and p-type GaAs, In0.53Ga0.47As, InAs, and InSb substrates, along with the effect of a thin germanium interfacial passivation layer. We found that MOSCAPs on all n-type substrates showed good C-V characteristics with small frequency dispersion (<10% and <200 mV). However, MOSCAPs on p-type GaAs and In0.53Ga0.47As substrates exhibited poor C-V characteristics implying severe Fermi level pinning, as has also been seen for p-type InP substrate. On the other hand, MOSCAPs on p-type InAs and InSb substrates, known as smaller bandgap materials, showed good C-V characteristics. We also present plausible mechanism for Fermi level pinning and interface characteristics.
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84.32.Tt Capacitors

Morphological and chemical optimization of ex situ NH4F (40%) conditioned Si(111)-(1×1):H

M. Lublow, T. Stempel, K. Skorupska, A. G. Muñoz, M. Kanis, and H. J. Lewerenz

Appl. Phys. Lett. 93, 062112 (2008); http://dx.doi.org/10.1063/1.2972142 (3 pages) | Cited 7 times

Online Publication Date: 15 August 2008

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Synchrotron radiation photoelectron spectroscopy was employed to investigate the chemical state of Si(111) surfaces upon anisotropic etching in concentrated NH4F solution. Minute amounts of oxidized silicon were detected and attributed to the fast Si–H–OH formation at atomic steps. Combining in situ optical and scanning probe techniques, consecutive chemical treatments were developed to achieve optimized morphological and chemical surface properties. Native oxides and a stressed SiO2/Si layer are removed by a two-step NH4F treatment leading to a terraced surface without triangular etch pits; subsequently, silicon in the Si1+/2+/3+ valence states is dissolved by HF (50%) while the surface topography is preserved.
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68.35.B- Structure of clean surfaces (and surface reconstruction)
79.60.Bm Clean metal, semiconductor, and insulator surfaces
81.65.Cf Surface cleaning, etching, patterning
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