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7 Jan 2008

Volume 92, Issue 1, Articles (01xxxx)

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Appl. Phys. Lett. 92, 011101 (2008); http://dx.doi.org/10.1063/1.2828458 (3 pages)

F. Pedaci, S. Barland, E. Caboche, P. Genevet, M. Giudici, J. R. Tredicce, T. Ackemann, A. J. Scroggie, W. J. Firth, G.-L. Oppo, G. Tissoni, and R. Jäger
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Atomic-layer-deposited nanostructures for graphene-based nanoelectronics

Y. Xuan, Y. Q. Wu, T. Shen, M. Qi, M. A. Capano, J. A. Cooper, and P. D. Ye

Appl. Phys. Lett. 92, 013101 (2008); http://dx.doi.org/10.1063/1.2828338 (3 pages) | Cited 30 times

Online Publication Date: 2 January 2008

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Graphene is a hexagonally bonded sheet of carbon atoms that exhibits superior transport properties with a velocity of 108 cm/s and a room-temperature mobility of >15 000 cm2/V s. How to grow gate dielectrics on graphene with low defect states is a challenge for graphene-based nanoelectronics. Here, we present the growth behavior of Al2O3 and HfO2 films on highly ordered pyrolytic graphite (HOPG) by atomic layer deposition (ALD). To our surprise, large numbers of Al2O3 and HfO2 nanoribbons, with dimensions of 5–200 nm in width and >50 μm in length, are observed on HOPG surfaces at growth temperature between 200 and 250 °C. This is due to the large numbers of step edges of graphene on HOPG surfaces, which serve as nucleation sites for the ALD process. These Al2O3 and HfO2 nanoribbons can be used as hard masks to generate graphene nanoribbons or as top-gate dielectrics for graphene devices. This methodology could be extended to synthesize insulating, semiconducting, and metallic nanostructures and their combinations.
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77.55.-g Dielectric thin films
68.55.A- Nucleation and growth
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
61.46.Hk Nanocrystals

Light-induced instability in current conduction of aluminum nitride thin films embedded with Al nanocrystals

Z. Liu, T. P. Chen, Y. Liu, L. Ding, M. Yang, J. I. Wong, Z. H. Cen, Y. B. Li, S. Zhang, and S. Fung

Appl. Phys. Lett. 92, 013102 (2008); http://dx.doi.org/10.1063/1.2828691 (3 pages) | Cited 3 times

Online Publication Date: 2 January 2008

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Al nanocrystals (nc-Al) embedded in AlN thin films have been synthesized by rf magnetron sputtering. The influence of ultraviolet (UV) illumination on electrical characteristics of the nc-Al/AlN thin film system has been investigated. It is shown that the UV illumination could lead to a random change in the conductance of the thin film system. The change in the conductance is attributed to the charge trapping and detrapping in the nc-Al due to the UV illumination.
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73.61.Ey III-V semiconductors
81.16.-c Methods of micro- and nanofabrication and processing
81.15.Cd Deposition by sputtering
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
78.66.Hf II-VI semiconductors

Optical beam focusing by a single subwavelength metal slit surrounded by chirped dielectric surface gratings

Seyoon Kim, Yongjun Lim, Hwi Kim, Junghyun Park, and Byoungho Lee

Appl. Phys. Lett. 92, 013103 (2008); http://dx.doi.org/10.1063/1.2828716 (3 pages) | Cited 45 times

Online Publication Date: 2 January 2008

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A method for optical beam focusing by a single subwavelength metal slit surrounded by surface gratings is proposed. In our proposed method, the period of each surface grating is chirped so that the radiation fields of surface plasmon polaritons can be controlled to make a beam spot at the desired focal length. Through our proposed method, it is numerically shown that we can make a beam spot which is located at the several times of wavelength distance from the slit, and its focal length can be controlled.
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73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
71.36.+c Polaritons (including photon-phonon and photon-magnon interactions)
42.79.Dj Gratings
41.85.Lc Particle beam focusing and bending magnets, wiggler magnets, and quadrupoles

Observation of laser-induced surface waves on flat silicon surface

Takuro Tomita, Yasuhiro Fukumori, Keita Kinoshita, Shigeki Matsuo, and Shuichi Hashimoto

Appl. Phys. Lett. 92, 013104 (2008); http://dx.doi.org/10.1063/1.2828983 (3 pages) | Cited 14 times

Online Publication Date: 2 January 2008

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We found that irradiation by a single femtosecond laser pulse produced a surface wave structure on a (100) silicon surface. The surface wave structure bearing a concentric shape was produced only in the edge regions in the direction of the electric field from the center. The increase in the number of irradiating pulses allowed the concentric structure gradually to align perpendicularly to the laser beam’s electric field. The period of the surface wave structure was nearly equal to the wavelength of the irradiating laser pulse. In this accord, we propose that this structure is a precursor of ripple formation.
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79.20.Ds Laser-beam impact phenomena
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)

Charge storage characteristics in metal-oxide-semiconductor memory structure based on gradual Ge1−xSix/Si heteronanocrystals

Jin Lu, Zheng Zuo, Yubin Chen, Yi Shi, Lin Pu, and Youdou Zheng

Appl. Phys. Lett. 92, 013105 (2008); http://dx.doi.org/10.1063/1.2828693 (3 pages) | Cited 6 times

Online Publication Date: 3 January 2008

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Charge storage characteristics in the metal-oxide-semiconductor memory structure based on gradual Ge1−xSix/Si heteronanocrystals (HNCs) have been investigated by using capacitance-voltage measurements. The gradual Ge1−xSix/Si HNCs on ultrathin SiO2 were fabricated through combining self-assembled growth and selective chemical etching technique. The observations demonstrate that the holes reach a longer retention time even with an ultrathin tunnel oxide, owing to the high band offset at the valence band between Ge and Si.
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84.32.Tt Capacitors
85.30.Tv Field effect devices
84.30.Sk Pulse and digital circuits
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
73.63.Bd Nanocrystalline materials

Effective metal dispersion in pyridinelike nitrogen doped graphenes for hydrogen storage

Gyubong Kim, Seung-Hoon Jhi, and Noejung Park

Appl. Phys. Lett. 92, 013106 (2008); http://dx.doi.org/10.1063/1.2828976 (3 pages) | Cited 24 times

Online Publication Date: 3 January 2008

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We study the pyridinelike nitrogen-doped graphene (PNG) with dispersed transition metal (TM) atoms as a potential hydrogen storage medium using the pseudopotential density functional method. It is found that highly localized states near the Fermi level, which are derived from the nitrogen defects, contribute to strong TM bindings and favorable hydrogen adsorption in the PNG. The strong TM binding prevents the metal aggregation and improves the material stability. The hydrogen molecular binding energy in TM+PNG complex is shown to be optimistic for room temperature storage and release.
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84.60.-h Direct energy conversion and storage
71.20.Ps Other inorganic compounds
71.15.Mb Density functional theory, local density approximation, gradient and other corrections
71.15.Dx Computational methodology (Brillouin zone sampling, iterative diagonalization, pseudopotential construction)
68.43.Mn Adsorption kinetics
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces

Reflow dynamics of thin patterned viscous films

T. Leveder, S. Landis, and L. Davoust

Appl. Phys. Lett. 92, 013107 (2008); http://dx.doi.org/10.1063/1.2828986 (3 pages) | Cited 6 times

Online Publication Date: 3 January 2008

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This letter presents a study of viscous smoothening dynamics of a nanopatterned thin film. Ultrathin film manufacturing processes appearing to be a key point of nanotechnology engineering and numerous studies have been recently led in order to exhibit driving parameters of this transient surface motion, focusing on time scale accuracy method. Based on nanomechanical analysis, this letter shows that controlled shape measurements provided much more detailed information about reflow mechanism. Control of reflow process of any complex surface shape, or measurement of material parameter as thin film viscosity, free surface energy, or even Hamaker constant are therefore possible.
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68.03.Cd Surface tension and related phenomena
68.55.am Polymers and organics
81.16.Rf Micro- and nanoscale pattern formation

Polarization dependent coupling of surface plasmon on a one-dimensional Ag grating with an InGaN/GaN dual-quantum-well structure

Kun-Ching Shen, Cheng-Yen Chen, Chi-Feng Huang, Jhy-Yang Wang, Yen-Cheng Lu, Yean-Woei Kiang, C. C. Yang, and Ying-Jay Yang

Appl. Phys. Lett. 92, 013108 (2008); http://dx.doi.org/10.1063/1.2829794 (3 pages) | Cited 15 times

Online Publication Date: 3 January 2008

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The authors report the observation of a polarization-dependent surface plasmon (SP) feature on a one-dimensional Ag-grating structure through the SP coupling with an InGaN/GaN dual-quantum-well structure closely below the metal grating. Polarized photon output is observed because only the momentum matching condition of the SP mode propagating in the direction perpendicular to the grating grooves can be reached through the diffraction of the fabricated grating and, thus, the SP radiation efficiency is significantly enhanced only in this polarization. The dispersion curve of the observed SP mode shows a group velocity of 2.4×108 m/s, which manifests the SP characteristics in the air/Ag/GaN grating structure.
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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
78.55.Cr III-V semiconductors

Fullerene thermal insulation for phase change memory

Cheolkyu Kim, Dong-Seok Suh, Kijoon H. P. Kim, Youn-Seon Kang, Tae-Yon Lee, Yoonho Khang, and David G. Cahill

Appl. Phys. Lett. 92, 013109 (2008); http://dx.doi.org/10.1063/1.2830002 (3 pages) | Cited 14 times

Online Publication Date: 3 January 2008

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Phase change random access memory (PRAM) is unique among semiconductor devices because heat is intrinsic to the operation of the device, not just a by-product. Here, we apply a material that is exotic in the context of typical semiconductor devices but has highly desirable properties for PRAM. Thin films of C60 are semiconducting and show very low thermal conductance. By inserting a C60 layer between the phase change material and the metal electrode, we dramatically reduced the heat dissipation and, thereby, the operating current. A PRAM device incorporating a C60 layer operated stably for more than 105 cycles.
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85.30.-z Semiconductor devices

Amino-acid-assisted synthesis and size-dependent magnetic behaviors of hematite nanocubes

Huaqiang Cao, Guozhi Wang, Jamie H. Warner, and Andrew A. R. Watt

Appl. Phys. Lett. 92, 013110 (2008); http://dx.doi.org/10.1063/1.2830699 (3 pages) | Cited 13 times

Online Publication Date: 4 January 2008

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This article reports the amino-acid-assisted synthesis and size-dependent magnetic properties of hematite nanocubes. The products were characterized using x-ray diffraction, Raman spectroscopy, transmission electron microscopy (TEM), and high-resolution TEM. The magnetic behavior of hematite nanocubes was studied using a vibrating sample magnetometer at room temperature. The sizes of hematite nanocubes were controlled by tuning the reaction parameters. The amino acid has double-hydrophilic functional groups, –NH2 and –COOH, which are utilized to control the growth and final size of hematite nanocubes. We show that utilizing biomolecules in chemical synthesis is a useful method for tailoring the physical properties of nanomaterials.
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81.16.-c Methods of micro- and nanofabrication and processing
61.46.-w Structure of nanoscale materials
78.30.Jw Organic compounds, polymers
82.30.-b Specific chemical reactions; reaction mechanisms
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
81.10.Dn Growth from solutions

Spatially resolved photoluminescence mapping of single CdS nanosheets

H. Rho, K.-Y. Lee, T. B. Hoang, L. V. Titova, A. Mishra, L. M. Smith, H. E. Jackson, J. M. Yarrison-Rice, Y.-J. Choi, K. J. Choi, and J.-G. Park

Appl. Phys. Lett. 92, 013111 (2008); http://dx.doi.org/10.1063/1.2828707 (3 pages) | Cited 5 times

Online Publication Date: 4 January 2008

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We have utilized spatially resolved low temperature photoluminescence to probe the electronic states and structural symmetries of individual single crystalline CdS nanosheets. Spatially resolved photoluminescence imaging of a single CdS nanosheet reveals a distinctive spectral variation across the nanosheet. We observe A-like exciton states which emit most strongly near the outer edges of the 5 μm wide nanosheet, while B-like exciton states emit most strongly along the center region of the 30 μm long axis of the nanosheet.
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78.55.Et II-VI semiconductors
61.46.Df Structure of nanocrystals and nanoparticles ("colloidal" quantum dots but not gate-isolated embedded quantum dots)
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
71.35.-y Excitons and related phenomena
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems

A megahertz nanomechanical resonator with room temperature quality factor over a million

Scott S. Verbridge, Harold G. Craighead, and Jeevak M. Parpia

Appl. Phys. Lett. 92, 013112 (2008); http://dx.doi.org/10.1063/1.2822406 (3 pages) | Cited 54 times

Online Publication Date: 4 January 2008

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We demonstrate the fabrication and operation of high aspect ratio tensile stressed silicon nitride string resonators. We explore the parameter space of small cross sections, on the order of 100 nm, and long lengths up to 325 μm, demonstrating that such high aspect ratio resonators can be made with standard wet release processing using a material with internal tensile stress. Room temperature quality factors exceed one million at frequencies above 1 MHz. The utility of such high quality factor flexural resonators to probe the interaction of high frequency nanoscale devices with rarefied gases is demonstrated.
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85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
84.30.Ng Oscillators, pulse generators, and function generators
85.35.-p Nanoelectronic devices

Enhanced charge carrier generation in dye sensitized solar cells by nanoparticle plasmons

Carl Hägglund, Michael Zäch, and Bengt Kasemo

Appl. Phys. Lett. 92, 013113 (2008); http://dx.doi.org/10.1063/1.2830817 (3 pages) | Cited 77 times

Online Publication Date: 4 January 2008

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An interesting possibility to improve the conversion and cost efficiencies of photovoltaic solar cells is to exploit the large optical cross sections of localized (nanoparticle) surface plasmon resonances (LSPRs). We have investigated this prospect for dye sensitized solar cells. Photoconductivity measurements were performed on flat TiO2 films, sensitized by a combination of dye molecules and arrays of nanofabricated elliptical gold disks. An enhanced dye charge carrier generation rate was found and shown to derive from the LSPR contribution by means of the polarization dependent resonance frequency in the anisotropic, aligned gold disks.
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84.60.Jt Photoelectric conversion
81.07.Bc Nanocrystalline materials
78.68.+m Optical properties of surfaces
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
73.50.Pz Photoconduction and photovoltaic effects
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
73.25.+i Surface conductivity and carrier phenomena
73.22.Lp Collective excitations

Tungsten oxide/tungsten nanocrystals for nonvolatile memory devices

C. H. Chen, T. C. Chang, I. H. Liao, P. B. Xi, Joe Hsieh, Jason Chen, Tensor Huang, S. M. Sze, U. S. Chen, and J. R. Chen

Appl. Phys. Lett. 92, 013114 (2008); http://dx.doi.org/10.1063/1.2822401 (3 pages) | Cited 5 times

Online Publication Date: 7 January 2008

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In this work, the fabrication of WO3/W nanocrystals for nonvolatile memory devices has been achieved via rapid thermal oxidation of tungsten silicide. Amorphous Si and WSix (x = 2.7) layers were deposited onto the tunneling oxide and sequentially oxidized to form well-shaped WO3/W nanocrystals. The mean size of WO3/W nanocrystals is ∼ 8.4 nm, while density is ∼ 1.57×1011 cm−2. Moreover, the nonvolatile memory device for WO3/W nanocrystals exhibits ∼ 0.53 V threshold voltage shift under 1 V/(−5 V) operation. The sample without capping a-Si layer was also fabricated for comparison. By material analyses, reasonable formation mechanisms are proposed in this letter.
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81.07.Bc Nanocrystalline materials
81.65.Mq Oxidation
84.30.Sk Pulse and digital circuits

Electron field emission from nanostructured cubic boron nitride islands

Kungen Teii, Seiichiro Matsumoto, and John Robertson

Appl. Phys. Lett. 92, 013115 (2008); http://dx.doi.org/10.1063/1.2830006 (3 pages) | Cited 12 times

Online Publication Date: 7 January 2008

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Nanocrystal-assembled cubic boron nitride (cBN) islands are formed by using low-energy ( ∼ 20 eV) ion irradiation in an inductively coupled fluorine-containing plasma. The temporal evolution of surface morphology and roughness reveals three-dimensional island growth for initial sp2-bonded BN and subsequent cBN, accompanied by a high frequency of renucleation. The formation of cBN islands enhances the field emission and reduces the turn-on field down to around 9 V/μm due to an increase in the island-related field. The results demonstrate the high potential of cBN for field emitters, comparable to other wide band gap semiconductors.
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81.07.Bc Nanocrystalline materials
79.70.+q Field emission, ionization, evaporation, and desorption
61.82.Rx Nanocrystalline materials

Triangular lattice plasmonic photonic band gaps in subwavelength metal-insulator-metal waveguide structures

Amir Hosseini, Hamid Nejati, and Yehia Massoud

Appl. Phys. Lett. 92, 013116 (2008); http://dx.doi.org/10.1063/1.2830018 (3 pages) | Cited 2 times

Online Publication Date: 7 January 2008

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We present a slablike photonic crystal with two-dimensional lattice structure, which exhibits subwavelength light confinement in the transverse direction perpendicular to the lattice plane based on the metal-insulator-metal (MIM) configuration. Using a modified implementation of the plane wave expansion method, we calculate the band structure created by a periodic modulation in the dielectric region of a MIM waveguide. The resulting band structure is verified by finite-difference time-domain simulations. We show that the MIM photonic crystal can provide a wider band gap compared to that of the two-dimensional photonic crystals.
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73.40.Rw Metal-insulator-metal structures
42.70.Qs Photonic bandgap materials

Theory and experiment of step bunching on misoriented GaAs(001) during metalorganic vapor-phase epitaxy

A. L.-S. Chua, E. Pelucchi, A. Rudra, B. Dwir, E. Kapon, A. Zangwill, and D. D. Vvedensky

Appl. Phys. Lett. 92, 013117 (2008); http://dx.doi.org/10.1063/1.2832370 (3 pages) | Cited 4 times

Online Publication Date: 7 January 2008

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We present experiments and an accompanying theory for the growth modes during metalorganic vapor-phase epitaxy on vicinal GaAs(001). Our theory is based on a model that takes account of deposition, diffusion, and dissociation of molecular precursors, and the diffusion and step incorporation of atoms released by the precursors. The experimental conditions for island nucleation and growth, step flow, and step bunching are reproduced by this model, with the step bunching instability caused by the difference in molecular dissociation from above and below step edges.
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68.55.ag Semiconductors
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.15.Kk Vapor phase epitaxy; growth from vapor phase

Thermophysical characteristics of water-in-FC72 nanoemulsion fluids

Z. H. Han and B. Yang

Appl. Phys. Lett. 92, 013118 (2008); http://dx.doi.org/10.1063/1.2830334 (3 pages) | Cited 3 times

Online Publication Date: 7 January 2008

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The use of solid particles has long been a common way of increasing fluid thermal conductivity. Here, nanoemulsion fluids—dispersions of liquid nanodroplets—are proposed. As an example, water-in-FC72 nanoemulsion fluids are developed, and their thermophysical properties and impact on natural convective heat transfer are investigated experimentally. The increase in conductivity and viscosity of the fluids is found to be nonlinear with water loading, indicating an important role of the hydrodynamic interaction and aggregation of nanodroplets. A very remarkable increase in effective specific heat—about 126% for 12 vol % water loading—occurs in the fluids due to melting-freezing transition of water nanodroplets.
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82.70.Kj Emulsions and suspensions
66.25.+g Thermal conduction in nonmetallic liquids
66.20.-d Viscosity of liquids; diffusive momentum transport
47.55.D- Drops and bubbles
65.20.-w Thermal properties of liquids
64.70.dj Melting of specific substances

Properties of YMnO3 self-assembled nanocrystalline prisms on GaN

Cameron Keenan, Sandeep Chandril, Thomas H. Myers, David Lederman, E. Ramos-Moore, and A. L. Cabrera

Appl. Phys. Lett. 92, 013119 (2008); http://dx.doi.org/10.1063/1.2831003 (3 pages) | Cited 4 times

Online Publication Date: 7 January 2008

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Growth of YMnO3 on GaN (0001) using molecular beam epitaxy at temperatures greater than 850 °C resulted in the spontaneous formation of crystalline prisms, ranging from 20 to 60 nm in height and 50 to 500 nm in lateral size, surrounded by a 6 nm thick continuous YMnO3 film. The local dielectric properties were measured using scanning surface probe microscopy. The prisms were ferroelectric at room temperature and their ferroelectric properties were enhanced for taller prisms. This is consistent with these structures being less constrained than the continuous layer, which is clamped by the surrounding unpolarized film.
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81.16.Dn Self-assembly
68.55.-a Thin film structure and morphology
61.46.Hk Nanocrystals
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
77.80.-e Ferroelectricity and antiferroelectricity
77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.
77.22.-d Dielectric properties of solids and liquids

Electrical characteristics of layered palladium alkanethiolates by conducting atomic force microscopy

Neena Susan John, S. K. Pati, and G. U. Kulkarni

Appl. Phys. Lett. 92, 013120 (2008); http://dx.doi.org/10.1063/1.2828340 (3 pages) | Cited 1 time

Online Publication Date: 8 January 2008

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Current-voltage measurements on individual Pd(II) alkanethiolate nanostructures of varying bilayer thicknesses (hexyl to hexadecyl) employing conducting atomic force microscopy have shown the presence of a low current region near zero bias, the width of which increases with the bilayer thickness. The resistance in this region varies exponentially with the bilayer thickness with a low decay parameter value of 0.2±0.04 Å−1 indicating a long-range nonresonant tunneling through the alkyl chains. The changeover from low current to high current with increasing bias is accompanied by a negative differential resistance feature, which arises due to Pd–S charge transfer.
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73.63.Bd Nanocrystalline materials
72.20.Fr Low-field transport and mobility; piezoresistance
61.46.-w Structure of nanoscale materials
73.40.Gk Tunneling

Optical properties of InP nanowires on Si substrates with varied synthesis parameters

Linus C. Chuang, Michael Moewe, Shanna Crankshaw, and Connie Chang-Hasnain

Appl. Phys. Lett. 92, 013121 (2008); http://dx.doi.org/10.1063/1.2832643 (3 pages) | Cited 22 times

Online Publication Date: 8 January 2008

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We report the effect of synthesis parameters on the physical appearance and optical properties of InP nanowires (NWs) grown on Si substrates by metal-organic chemical vapor deposition. A strong dependence on the group V to III precursor ratio is observed on the NW shape and, consequently, its photoluminescence (PL). Narrow, uniform-diameter NWs are achieved with an optimized V/III ratio. The uniform NWs exhibit PL widths as low as 1.4 meV. Their peak wavelength does not vary much with excitation, which is important for NW lasers on Si. These characteristics are attributed to the one-dimensional density of states in uniform-diameter NWs.
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78.67.Lt Quantum wires
81.16.-c Methods of micro- and nanofabrication and processing
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
78.55.Cr III-V semiconductors
71.20.Nr Semiconductor compounds

Independently addressable fields of porous anodic alumina embedded in SiO2 on Si

Aaron D. Franklin, David B. Janes, Jonathan C. Claussen, Timothy S. Fisher, and Timothy D. Sands

Appl. Phys. Lett. 92, 013122 (2008); http://dx.doi.org/10.1063/1.2831002 (3 pages) | Cited 6 times

Online Publication Date: 8 January 2008

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Fields of thin-film porous anodic alumina (PAA) are fabricated within a SiO2 support and on independently addressable underlying metal pads. The underlying metallization provides a means for unique postprocessing to be performed on the PAA fields. Customized postprocessing is demonstrated with the synthesis of single-walled carbon nanotubes (SWCNTs) from an embedded catalyst in the PAA, followed by selective decoration of the SWCNTs from different PAA fields with dissimilar nanoparticles. Achieving uniquely functionalized fields of PAA on a single chip provides a scalable integration platform to be used in multiplexed chemical and biological sensing or nanoelectronic devices.
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81.65.-b Surface treatments
82.45.Cc Anodic films
61.46.Df Structure of nanocrystals and nanoparticles ("colloidal" quantum dots but not gate-isolated embedded quantum dots)
61.43.Gt Powders, porous materials
85.35.-p Nanoelectronic devices

Noise thermometry and electron thermometry of a sample-on-cantilever system below 1 Kelvin

A. C. Bleszynski-Jayich, W. E. Shanks, and J. G. E. Harris

Appl. Phys. Lett. 92, 013123 (2008); http://dx.doi.org/10.1063/1.2821828 (3 pages) | Cited 7 times

Online Publication Date: 9 January 2008

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We have used two types of thermometry to study thermal fluctuations in a microcantilever-based system below 1 K. We measured the temperature of a cantilever’s macroscopic degree of freedom (via the Brownian motion of its lowest flexural mode) and its microscopic degrees of freedom (via the electron temperature of a metal sample mounted on the cantilever). We also measured both temperatures’ response to a localized heat source. We find that it is possible to maintain thermal equilibrium between these two temperatures and a refrigerator down to at least 300 mK. These results are promising for ongoing experiments to probe quantum effects using micromechanical devices.
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07.10.Cm Micromechanical devices and systems
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
07.20.Mc Cryogenics; refrigerators, low-temperature detectors, and other low-temperature equipment

Etching of nanopatterns in silicon using nanopantography

Lin Xu, Azeem Nasrullah, Zhiying Chen, Manish Jain, Paul Ruchhoeft, Demetre J. Economou, and Vincent M. Donnelly

Appl. Phys. Lett. 92, 013124 (2008); http://dx.doi.org/10.1063/1.2828208 (3 pages) | Cited 4 times

Online Publication Date: 9 January 2008

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Nanopantography is a technique for parallel writing of nanopatterns over large areas. A broad ion beam impinges on a substrate containing many microfabricated electrostatic lenses that focus ions to spots at the substrate surface. Here, etching of nanopatterns is demonstrated. The substrate was continuously titled about x and y axes with 0.11° precision, corresponding to a translation of the ion foci of 1.5 nm on the substrate. With tilting in one direction, 15 nm full width at half maximum trenches 45 nm deep were etched into a Si wafer using an Ar+ beam in a Cl2 ambient. T-shaped patterns were etched by tilting the substrates in two directions.
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81.16.Rf Micro- and nanoscale pattern formation
81.65.Cf Surface cleaning, etching, patterning

Depth sectioning of individual dopant atoms with aberration-corrected scanning transmission electron microscopy

Huolin L. Xin, Varat Intaraprasonk, and David A. Muller

Appl. Phys. Lett. 92, 013125 (2008); http://dx.doi.org/10.1063/1.2828990 (3 pages) | Cited 16 times

Online Publication Date: 9 January 2008

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The ability to detect individual impurity atoms has been greatly enhanced by the development of aberration-corrected electron microscopes. The reduced depth of focus potentially enables three-dimensional reconstructions of impurity atoms from through-focal series. We test the robustness of this depth-sectioning method for detecting impurity atoms in gate oxides using multislice simulations. For amorphous materials, dopants can be reliably imaged, and are accurately described by a simpler three-dimensional linear imaging model. For crystalline materials, however, channeling artifacts can render the signal uninterpretable. These artifacts can be eliminated by orienting the crystal slightly off the zone axis, which still preserves atomic resolution.
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61.72.U- Doping and impurity implantation
61.72.up Other materials
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