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

9 Nov 2009

Volume 95, Issue 19, Articles (19xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 95, 193101 (2009); http://dx.doi.org/10.1063/1.3258663 (3 pages)

L. Gaudreau, A. Kam, G. Granger, S. A. Studenikin, P. Zawadzki, and A. S. Sachrajda
Enlarge Image | Read More
Return to All Sections
back to top
RSS Feeds

Geometry dependent current-voltage characteristics of ZnO nanostructures: A combined nonequilibrium Green’s function and density functional theory study

Zhiwen Yang, Bin Wen, Roderick Melnik, Shan Yao, and Tingju Li

Appl. Phys. Lett. 95, 192101 (2009); http://dx.doi.org/10.1063/1.3259657 (3 pages) | Cited 4 times

Online Publication Date: 9 November 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Current-voltage (I-V) characteristics of different ZnO nanostructures were studied using a combined nonequilibrium Green’s function and density functional theory techniques with the two-probe model. It was found that I-V characteristics of ZnO nanostructures depend strongly on their geometry. For wurtzite ZnO nanowires, currents decrease with increasing lengths under the same applied voltage conditions. The I-V characteristics are similar for single-walled ZnO nanotubes and triangular cross section ZnO nanowires but they are different from I-V characteristics of hexagonal cross section ZnO nanowires. Finally, our results are discussed in the context of calculated transmission spectra and densities of states.
Show PACS
73.21.Hb Quantum wires
73.63.Nm Quantum wires
73.63.Fg Nanotubes
78.67.Ch Nanotubes
71.15.Mb Density functional theory, local density approximation, gradient and other corrections

Plasmon-enhanced heat dissipation in GaN-based two-dimensional channels

A. Matulionis, J. Liberis, I. Matulionienė, M. Ramonas, E. Šermukšnis, J. H. Leach, M. Wu, X. Ni, X. Li, and H. Morkoç

Appl. Phys. Lett. 95, 192102 (2009); http://dx.doi.org/10.1063/1.3261748 (3 pages) | Cited 11 times

Online Publication Date: 9 November 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Decay of nonequilibrium longitudinal optical (LO) phonons is investigated at room temperature in two-dimensional electron gas channels confined in nearly lattice-matched InAlN/AlN/GaN structures. A nonmonotonous dependence of the LO-phonon lifetime on the supplied electric power is reported for the first time and explained in terms of plasmon–LO-phonon resonance tuned by applied bias at a fixed sheet density (8×1012 cm−2). The shortest lifetime of 30±15 fs is found at the power of 20±10 nW/electron.
Show PACS
63.20.kk Phonon interactions with other quasiparticles
71.45.Gm Exchange, correlation, dielectric and magnetic response functions, plasmons
73.63.-b Electronic transport in nanoscale materials and structures

Superconducting tunneling spectroscopy of a carbon nanotube quantum dot

Travis Dirks, Yung-Fu Chen, Norman O. Birge, and Nadya Mason

Appl. Phys. Lett. 95, 192103 (2009); http://dx.doi.org/10.1063/1.3253705 (3 pages) | Cited 8 times

Online Publication Date: 10 November 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report results on superconducting tunneling spectroscopy of a carbon nanotube quantum dot. Using a three-probe technique that includes a superconducting tunnel probe, we map out changes in conductance due to band structure, excited states, and end-to-end bias. The superconducting probe allows us to observe enhanced spectroscopic features, such as robust signals of both elastic and inelastic cotunneling. We also see evidence of inelastic scattering processes inside the quantum dot.
Show PACS
73.40.Gk Tunneling
68.65.Hb Quantum dots (patterned in quantum wells)
71.20.Tx Fullerenes and related materials; intercalation compounds
61.46.Fg Nanotubes
74.50.+r Tunneling phenomena; Josephson effects

Highly efficient (Cs8V) superatom-based spin-polarizer

Haiying He, Ravindra Pandey, J. Ulises Reveles, Shiv N. Khanna, and Shashi P. Karna

Appl. Phys. Lett. 95, 192104 (2009); http://dx.doi.org/10.1063/1.3259646 (3 pages) | Cited 8 times

Online Publication Date: 10 November 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Quantum transport through molecules and the possibility to manipulate spin has generated tremendous excitement. Here, we demonstrate unusual spin transport through a molecule of two Cs8V magnetic superatoms. Calculations based on density functional theory and nonequilibrium Green’s function methods find a much higher current for the spin-down charge carriers relative to the spin-up carriers in the model Au–(Cs8V)–(Cs8V)–Au device system with almost 100% spin polarization, indicating a highly efficient spin polarizer. The new behavior is rooted in strong coupling of the localized magnetic core on V and the itinerant electrons of the Cs shell atoms leading to nearly full spin polarization.
Show PACS
73.40.Jn Metal-to-metal contacts
72.25.Ba Spin polarized transport in metals
72.25.Mk Spin transport through interfaces

Undoped vacuum annealed In2O3 thin films as a transparent conducting oxide

A. Dixit, C. Sudakar, R. Naik, V. M. Naik, and G. Lawes

Appl. Phys. Lett. 95, 192105 (2009); http://dx.doi.org/10.1063/1.3262963 (3 pages) | Cited 8 times

Online Publication Date: 10 November 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have investigated the structural, optical, and electrical properties of both as-grown and vacuum annealed In2O3 thin films. In contrast to the insulating as-prepared samples, vacuum annealed In2O3 films exhibit a metallic electrical conductivity with increased carrier concentration and mobility. We attribute the excess carriers to an oxygen deficiency introduced during vacuum annealing. Remarkably, these carrier densities seem to be stable under ambient conditions for at least two years. Optical spectroscopy measurements show a large optical transparency, greater than 80%, for both the as-prepared and vacuum annealed In2O3 films.
Show PACS
68.55.A- Nucleation and growth
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
78.66.-w Optical properties of specific thin films
72.20.Fr Low-field transport and mobility; piezoresistance
73.50.Dn Low-field transport and mobility; piezoresistance

Suppression of compensation from nitrogen and carbon related defects for p-type N-doped ZnO

Kun Tang, Shulin Gu, Shunming Zhu, Jiagao Liu, Hui Chen, Jiandong Ye, Rong Zhang, and Youdou Zheng

Appl. Phys. Lett. 95, 192106 (2009); http://dx.doi.org/10.1063/1.3262965 (3 pages) | Cited 13 times

Online Publication Date: 10 November 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In this letter, the authors performed a comprehensive study on suppression mechanism of compensation from nitrogen and carbon related complex defects in N-doped ZnO grown by metal-organic chemical vapor deposition. The chemical bonding information of donorlike substitutional complex defects, (NN)O and (NC)O, were restrained with low N/O ratio, leading to the conduction type conversion. High epitaxial temperature has more suppressing effect on the formation of desired acceptor NO than that of (NC)O, as evident by the decreasing hole concentration. Upon utilization of such suppression effect, this study provides a promising route to realize p-type ZnO.
Show PACS
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
61.72.uj III-V and II-VI semiconductors
72.20.Fr Low-field transport and mobility; piezoresistance
73.61.Ga II-VI semiconductors

Anisotropic electron spin relaxation in bulk GaN

J. H. Buß, J. Rudolph, F. Natali, F. Semond, and D. Hägele

Appl. Phys. Lett. 95, 192107 (2009); http://dx.doi.org/10.1063/1.3261755 (3 pages) | Cited 11 times

Online Publication Date: 11 November 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Electron spin dynamics in n-type c-oriented wurtzite GaN epilayers is studied by time-resolved Kerr-rotation measurements at T = 80 K. The electron spin lifetime shows a sudden increase if an external magnetic field is applied in the sample plane. This enhancement is explained by anisotropic Dyakonov–Perel spin relaxation in bulk GaN as a direct consequence of the anisotropy of spin-orbit coupling in semiconductors with wurtzite structure.
Show PACS
81.05.Ea III-V semiconductors
75.30.Gw Magnetic anisotropy
75.40.Gb Dynamic properties (dynamic susceptibility, spin waves, spin diffusion, dynamic scaling, etc.)
78.47.D- Time resolved spectroscopy (>1 psec)
68.55.ag Semiconductors
71.70.Ej Spin-orbit coupling, Zeeman and Stark splitting, Jahn-Teller effect

Cu–Cu diffusion bonding enhancement at low temperature by surface passivation using self-assembled monolayer of alkane-thiol

C. S. Tan, D. F. Lim, S. G. Singh, S. K. Goulet, and M. Bergkvist

Appl. Phys. Lett. 95, 192108 (2009); http://dx.doi.org/10.1063/1.3263154 (3 pages) | Cited 9 times

Online Publication Date: 11 November 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Self-assembled monolayer (SAM) of 1-hexanethiol is applied on copper (Cu) surface to retard surface oxidation during exposure in the ambient. This SAM layer can be desorbed effectively with an annealing step in inert N2 ambient to provide a clean Cu surface. Using this passivation method with SAM, wafers covered with thin Cu layer are passivated, stored, desorbed, and bonded at 250 °C. The bonded Cu layer presents clear evidence of substantial interdiffusion and grain growth despite prolonged exposure in the ambient. This method of passivation is proven to be effective and can be further optimized to enable high quality Cu–Cu direct bonding at low temperature for application in three-dimensional integration.
Show PACS
81.65.Rv Passivation
66.30.Ny Chemical interdiffusion; diffusion barriers
68.35.Fx Diffusion; interface formation
68.43.Jk Diffusion of adsorbates, kinetics of coarsening and aggregation

Fermi-level pinning at the interface between metals and nitrogen-doped Ge2Sb2Te5 examined by x-ray photoelectron spectroscopy

Lina Wei-Wei Fang, Rong Zhao, Jisheng Pan, Zheng Zhang, Luping Shi, Tow-Chong Chong, and Yee-Chia Yeo

Appl. Phys. Lett. 95, 192109 (2009); http://dx.doi.org/10.1063/1.3263953 (3 pages) | Cited 6 times

Online Publication Date: 12 November 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The metal/α-Ge2Sb2Te5 interface was examined using x-ray photoelectron spectroscopy. Doping Ge2Sb2Te5 with nitrogen leads to an increase in hole barrier height at the interface between metals and nitrogen-doped Ge2Sb2Te5. Hole barrier height at metal/α-Ge2Sb2Te5 interface is reduced slightly by increasing the work function of the metal. We observed significant pinning of metal Fermi level toward the valence band energy of undoped or nitrogen-doped Ge2Sb2Te5. This leads to low hole barrier height and good Ohmic contact formed between metals and α-Ge2Sb2Te5.
Show PACS
73.40.Ns Metal-nonmetal contacts
79.60.Jv Interfaces; heterostructures; nanostructures
61.72.up Other materials
84.30.Sk Pulse and digital circuits
73.30.+y Surface double layers, Schottky barriers, and work functions

Multichannel carbon nanotube field-effect transistors with compound channel layer

Changxin Chen, Wei Zhang, and Yafei Zhang

Appl. Phys. Lett. 95, 192110 (2009); http://dx.doi.org/10.1063/1.3263723 (3 pages) | Cited 1 time

Online Publication Date: 13 November 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A multichannel carbon nanotube field-effect transistor (MC-CNTFET) with compound channel layer has been built. In this MC-CNTFET, a dispersedly directed array of long single-walled carbon nanotubes (SWCNTs) is used as primary channel layer and a randomly aligned monolayer network of short SWCNTs acts as secondary set of “bridge” channel layer, which causes large numbers of short semiconducting percolation paths formed. The device exhibits a large on-state current of 2.01 mA and simultaneously retains a high current on/off ratio of 103–104. The function dependency of the on-state current on the density of long SWCNTs and length of short SWCNTs is also presented.
Show PACS
85.35.Kt Nanotube devices
81.07.De Nanotubes

Sulfur passivation of InN surface electron accumulation

L. R. Bailey, T. D. Veal, C. E. Kendrick, S. M. Durbin, and C. F. McConville

Appl. Phys. Lett. 95, 192111 (2009); http://dx.doi.org/10.1063/1.3263725 (3 pages) | Cited 5 times

Online Publication Date: 13 November 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The effects of treatment with ammonium sulfide ((NH4)2Sx) solution on the electronic properties of InN surfaces have been investigated with high resolution x-ray photoemission spectroscopy. The valence band, In 3d, and N 1s x-ray photoemission spectra show that the surface Fermi level decreases by approximately 0.15 eV with (NH4)2Sx-treatment. This corresponds to a reduction of the downward band bending with the surface sheet charge density decreasing by 30%.
Show PACS
81.65.Rv Passivation
72.20.Fr Low-field transport and mobility; piezoresistance
73.20.At Surface states, band structure, electron density of states
71.20.Nr Semiconductor compounds
79.60.Bm Clean metal, semiconductor, and insulator surfaces

g-factor and exchange energy in a few-electron lateral InGaAs quantum dot

M. Larsson, H. A. Nilsson, H. Hardtdegen, and H. Q. Xu

Appl. Phys. Lett. 95, 192112 (2009); http://dx.doi.org/10.1063/1.3264053 (3 pages) | Cited 4 times

Online Publication Date: 13 November 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report on the measurements of the g-factor and the exchange interaction of electrons in a few-electron lateral quantum dot formed in an InGaAs/InP semiconductor heterostructure. The spin filling sequence of the electron states in the dot is determined by magnetotransport measurements and parallel spin filling configurations are identified. The measured g-factor (for a magnetic field applied parallel to the InGaAs quantum-well layer) has a value in the range of |g∗| ≈ 2 to |g∗| ≈ 4 and is strongly level-dependent. By analysis of the energies of the states which favor a parallel spin filling, the lower bound of the exchange energy of electrons in the dot in the order of ∼ 210 μeV is extracted.
Show PACS
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
81.05.Ea III-V semiconductors
81.07.Ta Quantum dots
73.63.Kv Quantum dots
72.20.My Galvanomagnetic and other magnetotransport effects
71.70.Gm Exchange interactions

Effects of a Gd capping layer on electrical characteristics of metal-oxide-semiconductor field effect transistors with a TaC gate electrode and a HfSiON gate dielectric

Hong Bae Park, Chang Seo Park, Chang Yong Kang, Seung-Chul Song, Byoung Hun Lee, Tae-Young Jang, Tea Wan Kim, Jae Kyeong Jeong, and Rino Choi

Appl. Phys. Lett. 95, 192113 (2009); http://dx.doi.org/10.1063/1.3264086 (3 pages) | Cited 5 times

Online Publication Date: 13 November 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Effects of Gd capping of HfSiON gate dielectric on the characteristics of n metal-oxide-semiconductor field effect transistor (nMOSFET) with TaC gate electrode were investigated. MOSFETs with an in situ deposited Gd/TaC bilayer demonstrated a reduced equivalent oxide thickness, 0.9 nm, and low VTH, 0.25 V, compared with MOSFETs without Gd capping layer. Backside secondary ion mass spectroscopy revealed that Gd atoms were diffused into the high-k gate dielectric and interfacial layer between high-k dielectric and Si substrate. The dipole moment at the high-k/SiO2 interface due to Hf–O and RE–O bonds is used to explain the VTH change.
Show PACS
85.30.Tv Field effect devices

Disorder enhances thermoelectric figure of merit in armchair graphane nanoribbons

Xiaoxi Ni, Gengchiau Liang, Jian-Sheng Wang, and Baowen Li

Appl. Phys. Lett. 95, 192114 (2009); http://dx.doi.org/10.1063/1.3264087 (3 pages) | Cited 23 times

Online Publication Date: 13 November 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We study the thermoelectric property of graphane strips by using density functional theory calculations combined with the nonequilibrium Green’s function method. It is found that figure of merit (ZT) can be remarkably enhanced five times by randomly introducing hydrogen vacancies to the graphene nanoribon derivatives—armchair graphane nanoribbons. For 5 nm wide ribbons under certain conditions, ZT can be as high as 5.8 and depends on temperature linearly. The high ZT, low cost, and rapid advances in the synthesis of nanoscale graphene derivatives make carbon-based materials a viable choice for thermoelectric applications.
Show PACS
72.20.Pa Thermoelectric and thermomagnetic effects
73.63.Fg Nanotubes
61.72.jd Vacancies

Mapping out the distribution of electronic states in the mobility gap of amorphous zinc tin oxide

Peter T. Erslev, Eric S. Sundholm, Rick E. Presley, David Hong, John F. Wager, and J. David Cohen

Appl. Phys. Lett. 95, 192115 (2009); http://dx.doi.org/10.1063/1.3262962 (3 pages) | Cited 10 times

Online Publication Date: 13 November 2009

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Amorphous zinc tin oxide (ZTO) is a wide-band-gap (transparent) semiconductor which exhibits high electron mobilities irrespective of its disordered nature. Transient photocapacitance (TPC), drive level capacitance profiling (DLCP), and modulated photocurrent spectroscopy (MPC) were used to determine the electronic state distribution within the mobility gap of ZTO. Conduction band-tail and valence band-tail Urbach energies near 10 and 110 meV were obtained by MPC and TPC, respectively. DLCP indicated free carrier densities in the mid-1015 cm−3 range plus a 0.2eV wide band of defects 0.4eV from the conduction band. The MPC spectra for ZTO also disclosed a defect band near the conduction band-tail.
Show PACS
71.20.Nr Semiconductor compounds
72.20.Fr Low-field transport and mobility; piezoresistance
71.23.Cq Amorphous semiconductors, metallic glasses, glasses
61.72.-y Defects and impurities in crystals; microstructure
79.60.Bm Clean metal, semiconductor, and insulator surfaces
72.40.+w Photoconduction and photovoltaic effects
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close