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 Feb 2010

Volume 96, Issue 8, Articles (08xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 96, 081101 (2010); http://dx.doi.org/10.1063/1.3324885 (3 pages)

Wuzhou Song and Demetri Psaltis
Enlarge Image | Read More
Return to All Sections
back to top
RSS Feeds

Measurements of the sheet resistance and conductivity of thin epitaxial graphene and SiC films

J. Krupka and W. Strupinski

Appl. Phys. Lett. 96, 082101 (2010); http://dx.doi.org/10.1063/1.3327334 (3 pages) | Cited 13 times

Online Publication Date: 23 February 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Single postdielectric resonators operating on their quasi TE011 modes were used for the measurement of the surface resistance and conductivity of graphene films grown on semi-insulating SiC substrates. With this technique the surface resistance was measured with an uncertainty of ±5% and the conductivity was evaluated with an uncertainty equal to the uncertainty in determining the film thickness. The room temperature conductivity of the graphene films proved to be in the range 5×106 to 6.4×106 S/m.
Show PACS
72.80.Rj Fullerenes and related materials
73.25.+i Surface conductivity and carrier phenomena
84.37.+q Measurements in electric variables (including voltage, current, resistance, capacitance, inductance, impedance, and admittance, etc.)
72.20.-i Conductivity phenomena in semiconductors and insulators

A quantum dot spin injector with spin bias

Feng Chi, Xiao-Ning Dai, and Lian-Liang Sun

Appl. Phys. Lett. 96, 082102 (2010); http://dx.doi.org/10.1063/1.3327807 (3 pages) | Cited 7 times

Online Publication Date: 23 February 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We propose a spin injector consisting of a quantum dot (QD), which is coupled to two leads, to separate either spin-up or spin-down electrons from one lead into the other. Meanwhile, a single electron spin state can also be written into the QD. It works mainly due to the spin bias in one of the leads, which has been realized in recent experiments by Frolov et al. [Phys. Rev. Lett. 102, 116802 (2009) ; Nature (London) 458, 868 (2009)] , and the Coulomb blockade effect in the QD. This device is realizable with current technologies and may have practical use in spintronics or quantum processing.
Show PACS
85.35.Ds Quantum interference devices
85.75.-d Magnetoelectronics; spintronics: devices exploiting spin polarized transport or integrated magnetic fields
72.25.-b Spin polarized transport
73.21.La Quantum dots

Variation in hopping conduction across the magnetic transition in spinel Mn1.56Co0.96Ni0.48O4 films

Jing Wu, Zhiming Huang, Yun Hou, Yanqing Gao, and Junhao Chu

Appl. Phys. Lett. 96, 082103 (2010); http://dx.doi.org/10.1063/1.3318459 (3 pages) | Cited 4 times

Online Publication Date: 23 February 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The temperature dependent dc resistivity of spinel Mn1.56Co0.96Ni0.48O4 (MCN) films is measured in the range of 130–304 K. The hopping exponent p of small polaron hopping conduction shows a clear variation from a value of 0.46 in the paramagnetic to 0.91 in the ferromagnetic phase. In order to explain such variation, a model is proposed where Gaussian distributed localized electron states gradually withdraw from the Hubbard band gap below the magnetic transition as a result of increased magnetic order. This correlation between hopping conduction and magnetic order in MCN films may provide a possible approach to fabricate the devices which couple magnetic and electronic properties in one unit.
Show PACS
73.50.Dn Low-field transport and mobility; piezoresistance
73.61.-r Electrical properties of specific thin films
75.70.Ak Magnetic properties of monolayers and thin films
72.20.Ee Mobility edges; hopping transport
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)

Charge sensing in intrinsic silicon quantum dots

G. J. Podd, S. J. Angus, D. A. Williams, and A. J. Ferguson

Appl. Phys. Lett. 96, 082104 (2010); http://dx.doi.org/10.1063/1.3318463 (3 pages) | Cited 9 times

Online Publication Date: 23 February 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report charge sensing measurements on a silicon quantum dot with a nearby silicon single electron transistor (SET) acting as an electrometer. The devices are electrostatically formed in bulk silicon using surface gates. We show that as an additional electron is added onto the quantum dot, a charge is induced on the SET of approximately 0.2e. These measurements are performed in the many electron regime, where we can count in excess of 20 charge additions onto the quantum dot.
Show PACS
85.35.Gv Single electron devices
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
07.68.+m Photography, photographic instruments; xerography

Improved local oxidation of silicon carbide using atomic force microscopy

Yeong-Deuk Jo, Soo-Hyung Seo, Wook Bahng, Sang-Cheol Kim, Nam-Kyun Kim, Sang-Sig Kim, and Sang-Mo Koo

Appl. Phys. Lett. 96, 082105 (2010); http://dx.doi.org/10.1063/1.3327832 (3 pages) | Cited 3 times

Online Publication Date: 23 February 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The atomic force microscopy-based local oxidation (AFM-LO) of silicon carbide (SiC) is extremely difficult in general, mainly due to their physical hardness and chemical inactivity. Herein, we report the strongly enhanced AFM-LO of 4H-SiC at room temperature without the heating, chemicals or photoillumination. It is demonstrated that the increased tip loading force ( ∼ >100 nN) on the highly doped SiC can produce a high enough electric field ( ∼ 8×106 V/cm) under the cathode tip for transporting oxyanions, thereby leading to direct oxide growth on 4H-SiC. The doping concentration and electric field profile of the tip-SiC sample structures were further examined by two-dimensional numerical simulations.
Show PACS
81.65.Mq Oxidation
81.05.Hd Other semiconductors
61.72.up Other materials
68.37.Ps Atomic force microscopy (AFM)

Nonuniformity of electron density in In-rich InGaN films deduced from electrolyte capacitance-voltage profiling

A. Knübel, V. M. Polyakov, L. Kirste, and R. Aidam

Appl. Phys. Lett. 96, 082106 (2010); http://dx.doi.org/10.1063/1.3319511 (3 pages)

Online Publication Date: 23 February 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
InxGa1−xN films with 0.4 ≤ x ≤ 1 are analyzed using electrolyte-based capacitance-voltage technique. In-rich InxGa1−xN for x>0.4 samples exhibit a strong surface electron accumulation. At x = 0.4, the Fermi level at the surface is pinned to the conduction band edge indicating a crossover from surface accumulation to depletion. The measured Mott–Schottky plots are fitted using a model based on a Schrödinger–Poisson solver. By comparing the measured data to the fitting results, we conclude that a subsurface layer of ∼ 15 nm thickness with remarkably lower donor defect concentration is formed during the growth of InGaN films.
Show PACS
73.20.At Surface states, band structure, electron density of states
73.20.Hb Impurity and defect levels; energy states of adsorbed species
71.55.Eq III-V semiconductors
81.05.Ea III-V semiconductors

Scanning tunneling microscopy and spectroscopy of the electronic structure of dislocations in GaN/Si(111) grown by molecular-beam epitaxy

Ya-Ping Chiu, Bo-Chih Chen, Bo-Chao Huang, Min-Chuan Shih, and Li-Wei Tu

Appl. Phys. Lett. 96, 082107 (2010); http://dx.doi.org/10.1063/1.3319512 (3 pages) | Cited 8 times

Online Publication Date: 23 February 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
By using cross-sectional scanning tunneling microscopy, a correlation between the surface morphology and the corresponding electronic states of the dislocations terminated at the GaN(1math00) cleavage surfaces grown by molecular-beam epitaxy has been demonstrated. Both scanning tunneling spectroscopy and analysis of the dislocations on electronic structures suggest that regions surrounding dislocations register gap states in the fundamental band gap of GaN. Closely examining the recognition of the electronic structure reveals that the defect levels could provide the possibility of yellow luminescence, involving a transition from the conduction-band edge to a level at 1.2 eV above the valence band edge.
Show PACS
68.55.ag Semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
71.20.Nr Semiconductor compounds
81.05.Ea III-V semiconductors

Magnetic-field-controlled noise-activated switching in a nonlinear three-terminal nanojunction

F. Hartmann, D. Hartmann, P. Kowalzik, L. Gammaitoni, A. Forchel, and L. Worschech

Appl. Phys. Lett. 96, 082108 (2010); http://dx.doi.org/10.1063/1.3330861 (3 pages) | Cited 4 times

Online Publication Date: 23 February 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Magnetic-field-controlled switching of a nonlinear three-terminal nanojunction was studied. Noise-activated switching was observed, which depends sensitively on the strength of an external magnetic field. Such a functioning resembles a noise-activated nonlinear detector as proposed by Gammaitoni and Bulsara [Phys. Rev. Lett. 88, 230601 (2002)] for magnetic fields realized with a nanoelectronic device.
Show PACS
81.07.-b Nanoscale materials and structures: fabrication and characterization
81.16.Nd Micro- and nanolithography
85.40.Hp Lithography, masks and pattern transfer
81.65.Cf Surface cleaning, etching, patterning
85.35.-p Nanoelectronic devices
81.05.Ea III-V semiconductors

Investigation of hole-mobility in a polyfluorene copolymer by admittance spectroscopy

Siraye E. Debebe, Wendimagegn Mammo, Teketel Yohannes, Francesca Tinti, Alberto Zanelli, and Nadia Camaioni

Appl. Phys. Lett. 96, 082109 (2010); http://dx.doi.org/10.1063/1.3332481 (3 pages) | Cited 4 times

Online Publication Date: 24 February 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Transport of holes in a low band gap polyfluorene, APFO-Green6, was investigated by means of admittance spectroscopy in the modulation frequency range 1–106 Hz. At room temperature, hole mobility of APFO-Green6 is dependent on the applied electric field, as commonly observed in disordered organic materials. The excess capacitance toward low frequencies provides evidence for charge relaxation in trap levels. A dispersion parameter of 0.4 was achieved from the trend of hole transit times with the electric field.
Show PACS
83.80.Tc Polymer blends
82.70.-y Disperse systems; complex fluids
61.41.+e Polymers, elastomers, and plastics
81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials

Weak-antilocalization signatures in the magnetotransport properties of individual electrodeposited Bi Nanowires

N. Marcano, S. Sangiao, M. Plaza, L. Pérez, A. Fernández Pacheco, R. Córdoba, M. C. Sánchez, L. Morellón, M. R. Ibarra, and J. M. De Teresa

Appl. Phys. Lett. 96, 082110 (2010); http://dx.doi.org/10.1063/1.3328101 (3 pages) | Cited 6 times

Online Publication Date: 24 February 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We study the electrical resistivity of individual Bi nanowires of diameter 100 nm fabricated by electrodeposition using a four-probe method in the temperature range 5–300 K with magnetic fields up to 90 kOe. Low-resistance Ohmic contacts to individual Bi nanowires are achieved using a focused ion beam to deposit W-based nanocontacts. Magnetoresistance measurements show evidence for weak antilocalization at temperatures below 10 K, with a phase-breaking length of 100 nm.
Show PACS
73.63.Nm Quantum wires
73.40.Ns Metal-nonmetal contacts
81.15.Pq Electrodeposition, electroplating
82.45.Qr Electrodeposition and electrodissolution
72.15.Gd Galvanomagnetic and other magnetotransport effects
81.16.-c Methods of micro- and nanofabrication and processing

Electronic properties of two-dimensional hexagonal germanium

M. Houssa, G. Pourtois, V. V. Afanas’ev, and A. Stesmans

Appl. Phys. Lett. 96, 082111 (2010); http://dx.doi.org/10.1063/1.3332588 (3 pages) | Cited 12 times

Online Publication Date: 25 February 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The electronic properties of two-dimensional hexagonal germanium, so called germanene, are investigated using first-principles simulations. Consistent with previous reports, the surface is predicted to have a “poor” metallic behavior, i.e., being metallic with a low density of states at the Fermi level. It is found that biaxial compressively strained germanene is a gapless semiconductor with linear energy dispersions near the K points—like graphene. The calculated Fermi velocity of germanene is almost independent of the strain and is about 1.7×106 m/s, quite comparable to the value in graphene.
Show PACS
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
73.20.At Surface states, band structure, electron density of states
71.15.Mb Density functional theory, local density approximation, gradient and other corrections

Structured epitaxial graphene growth on SiC by selective graphitization using a patterned AlN cap

Miguel Rubio-Roy, Farhana Zaman, Yike Hu, Claire Berger, Michael W. Moseley, James D. Meindl, and Walt A. de Heer

Appl. Phys. Lett. 96, 082112 (2010); http://dx.doi.org/10.1063/1.3334683 (3 pages) | Cited 4 times

Online Publication Date: 25 February 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Electronic quality epitaxial graphene has been selectively grown on silicon carbide capped with a patterned aluminum nitride layer, providing a pathway to produce device structures that avoid lithographic patterning of graphene itself. Patterning of the cap exposes SiC where graphene will grow. Capped areas inhibit graphene growth and withstand graphitization temperatures up to 1420°C under 100 Pa of argon pressure. Graphene Hall bars were fabricated and characterized by scanning Raman spectroscopy, ellipsometry, and transport measurements. Hall-mobility is about 600 cm2/V s and can be further enhanced by fine tuning the argon pressure and improving the quality of SiC surface prior to graphitization.
Show PACS
81.16.-c Methods of micro- and nanofabrication and processing
72.20.My Galvanomagnetic and other magnetotransport effects
78.30.Hv Other nonmetallic inorganics
81.05.ue Graphene

Transient surface photovoltage of p-type Cu3BiS3

F. Mesa, G. Gordillo, Th. Dittrich, K. Ellmer, R. Baier, and S. Sadewasser

Appl. Phys. Lett. 96, 082113 (2010); http://dx.doi.org/10.1063/1.3334728 (3 pages) | Cited 3 times

Online Publication Date: 25 February 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Thin films of Cu3BiS3 were prepared by coevaporation. Hall-effect, Seebeck-effect, and surface photovoltage measurements show that Cu3BiS3 is a p-type semiconductor with Hall-mobility, free carrier concentration, and thermo-electric power of 4 cm2/V s, 2×1016 cm−3, and 0.73 mV/K, respectively. The work function was determined by Kelvin probe force microscopy to be (4.37±0.04) eV before and (4.57±0.01) eV after deposition of a thin In2S3 layer. Transient surface photovoltage measurements at variable excitation wavelength showed the importance of defect states below the band gap for charge separation and the opportunity for surface defect passivation by a very thin In2S3 layer. The band bending at the Cu3BiS3/In2S3 interface was obtained. The role of grain boundaries for charge transport and charge separation is discussed.
Show PACS
73.25.+i Surface conductivity and carrier phenomena
73.50.Pz Photoconduction and photovoltaic effects
72.40.+w Photoconduction and photovoltaic effects
72.20.Pa Thermoelectric and thermomagnetic effects
73.50.Lw Thermoelectric effects
72.20.My Galvanomagnetic and other magnetotransport effects
61.72.Mm Grain and twin boundaries
81.65.Rv Passivation
71.55.-i Impurity and defect levels
73.30.+y Surface double layers, Schottky barriers, and work functions

Electrical transport and low-temperature scanning tunneling microscopy of microsoldered graphene

V. Geringer, D. Subramaniam, A. K. Michel, B. Szafranek, D. Schall, A. Georgi, T. Mashoff, D. Neumaier, M. Liebmann, and M. Morgenstern

Appl. Phys. Lett. 96, 082114 (2010); http://dx.doi.org/10.1063/1.3334730 (3 pages) | Cited 9 times

Online Publication Date: 25 February 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Using the recently developed technique of microsoldering, we perform systematic transport studies of the influence of polymethylmethacrylate on graphene revealing a doping effect with a n-type dopant density Δn of up to Δn = 3.8×1012 cm−2 but negligible influence on mobility and hysteresis. Moreover, we show that microsoldered graphene is free of contamination and exhibits very similar intrinsic rippling as found for lithographically contacted flakes. Characterizing the microsoldered sample by scanning tunneling spectroscopy, we demonstrate a current induced closing of the phonon gap and a B-field induced double peak attributed to the 0 Landau level.
Show PACS
71.70.Di Landau levels
61.72.U- Doping and impurity implantation
68.35.B- Structure of clean surfaces (and surface reconstruction)

Molecular spin valve and spin filter composed of single-molecule magnets

L. Zhu, K. L. Yao, and Z. L. Liu

Appl. Phys. Lett. 96, 082115 (2010); http://dx.doi.org/10.1063/1.3319506 (3 pages) | Cited 14 times

Online Publication Date: 25 February 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We presented a theoretical study on the spin-polarized transport of one single-molecule magnet. The results show it has spin filter behavior, and can also be used as a molecular spin valve with large abnormal magnetoresistance, which is an excellent candidate for spintronics of molecular devices. It is also found that the steplike features with negative differential resistance in the I-V curve indeed originate from the discreteness and narrow features in the density of states of the molecular levels.
Show PACS
85.75.-d Magnetoelectronics; spintronics: devices exploiting spin polarized transport or integrated magnetic fields
72.20.My Galvanomagnetic and other magnetotransport effects
75.76.+j Spin transport effects
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)

TiO2 thin-film transistors fabricated by spray pyrolysis

Paul H. Wöbkenberg, Thilini Ishwara, Jenny Nelson, Donal D. C. Bradley, Saif A. Haque, and Thomas D. Anthopoulos

Appl. Phys. Lett. 96, 082116 (2010); http://dx.doi.org/10.1063/1.3330944 (3 pages) | Cited 14 times

Online Publication Date: 25 February 2010

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We demonstrate electron transporting thin-film transistors based on TiO2 films deposited from solution by spray pyrolysis under ambient atmosphere. The field-effect electron mobility is found to depend strongly on the device architecture and the type of source and drain electrodes employed. For optimized transistors a maximum mobility value of 0.05 cm2/V s is obtained. Furthermore, the TiO2 transistors show air-stable operating characteristics with a shelf life time of several months. This is the only report on electron transporting transistors based on thin-films of TiO2 deposited by spray pyrolysis. Such devices could be used for the study of charge carrier transport in TiO2 and other related materials.
Show PACS
85.30.Tv Field effect devices
81.15.Rs Spray coating techniques
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close