Customer Papers
This is a searchable database of papers written by our customers, using Cambridge NanoTech systems. If you are publishing a paper based on research done on a Cambridge NanoTech ALD system, please contact us. We would be pleased to include it in our database.Showing customer papers 1-10 of 33 Next
| LINK | Ondersma, J. W.; Hamann, T. W. |
| "Impedance Investigation of Dye-Sensitized Solar Cells Employing Outer-Sphere Redox Shuttles" | |
| Journal of Physical Chemistry C, 2010, 114, 638-645 | |
| Abstract: | Electrochemical impedance spectroscopy was used to investigate dye-sensitized solar cells (DSSCs) employing outer-sphere redox shuttles. A three-electrode cell was used to overcome limitations associated with a high charge transfer resistance at the counter electrode, accurately compare alumina coated and bare photoanodes, and compare DSSCs with different solution potentials. The effect of an alumina coating, which has been shown to improve the performance of such DSSCs, was determined by comparisons of the chemical capacitance, charge transport and charge recombination. Contrary to previous reports and our expectations, no evidence of recombination from surface states was observed at any potential range for either coated or uncoated electrodes, further confirmed with open circuit voltage decay measurements. Instead, even a single atomic layer deposition cycle of alumina acts as a tunneling barrier layer, which produces the decrease in recombination rate of electrons from the TiO2 to the oxidized redox shuttle. Impedance measurement results allowed calculation of charge transport times and lifetimes for DSSCs employing a series of cobalt bipyridyl redox shuttles. Comparisons of these transport times and lifetimes produce estimates of the effective charge diffusion lengths. The relative diffusion lengths are in excellent agreement with the photovoltaic response of the DSSCs studied; however, the magnitude appears to be a slight overestimate. |
| Address: | Hamann, TW Michigan State Univ, Dept Chem, E Lansing, MI 48824 USA Michigan State Univ, Dept Chem, E Lansing, MI 48824 USA Michigan State Univ, Dept Chem, E Lansing, MI 48824 USA |
| LINK | Prasittichai, C.; Hupp, J. T. |
| "Surface Modification of SnO2 Photoelectrodes in Dye-Sensitized Solar Cells: Significant Improvements in Photovoltage via Al2O3 Atomic Layer Deposition" | |
| Journal of Physical Chemistry Letters, 2010, 1, 1611-1615 | |
| Abstract: | We report here the exploitation of ultrathin layers of Al2O3 deposited via atomic layer deposition (ALD) on SnO2 photoanodes used in dye-sensitized solar cells featuring the I-3(-)/I- couple as the redox electrolyte. We find that a single ALD cycle of Al2O3 increases the lifetimes of injected electrons by more than 2 orders of magnitude. The modified SnO2 photoanode yields nearly a 2-fold improvement fill factor and a greater than 2-fold increase in open circuit photo voltage, with a slight increase in short-circuit photocurrent. The overall energy conversion efficiency increases by roughly 5-fold. The effects appear to arise primarly from passivation of reactive, low-energy tin oxide surface states, with band edge shifts and tunneling based blocking behavior playing only secondary roles. |
| Address: | Hupp, JT Northwestern Univ, Dept Chem, 2145 Sheridan Rd, Evanston, IL 60208 USA Northwestern Univ, Dept Chem, 2145 Sheridan Rd, Evanston, IL 60208 USA Northwestern Univ, Dept Chem, Evanston, IL 60208 USA Northwestern Univ, ANSER Ctr, Evanston, IL 60208 USA Argonne Natl Lab, Argonne, IL 60439 USA |
| LINK | Robinson, J. A.; LaBella, M.; Trumbull, K. A.; Weng, X. J.; Cavelero, R.; Daniels, T.; Hughes, Z.; Hollander, M.; Fanton, M.; Snyder, D. |
| "Epitaxial Graphene Materials Integration: Effects of Dielectric Overlayers on Structural and Electronic Properties" | |
| ACS Nano, 2010, 4, 2667-2672 | |
| Abstract: | We present the integration of epitaxial graphene with thin film dielectric materials for the purpose of graphene transistor development. The impact on epitaxial graphene structural and electronic properties following deposition of Al2O3, HfO2, TiO2, and Ta2O3 varies based on the choice of dielectric and deposition parameters. Each dielectric film requires the use of a nucleation layer to ensure uniform, continuous coverage on the graphene surface. Graphene quality degrades most severely following deposition of Ta2O3, while the deposition if TiO2 appears to improve the graphene carrier mobility. Finally, we discuss the potential of dielectric stack engineering for improved transistor performance. |
| Address: | Robinson, JA Penn State Univ, Ctr Electroopt, University Pk, PA 16802 USA Penn State Univ, Ctr Electroopt, University Pk, PA 16802 USA Penn State Univ, Ctr Electroopt, University Pk, PA 16802 USA Penn State Univ, Dept Mat Sci |
| LINK | Shanmugam, M.; Baroughi, M. F.; Galipeau, D. |
| "Effect of atomic layer deposited ultra thin HfO2 and Al2O3 interfacial layers on the performance of dye sensitized solar cells" | |
| Thin Solid Films, 2010, 518, 2678-2682 | |
| Abstract: | The objective of this work was to investigate the improvement in performance of dye sensitized solar cells (DSSCs) by depositing ultra thin metal oxides (hafnium oxide (HfO2) and aluminum oxide (Al2O3)) on mesoporous TiO2 photoelectrode using atomic layer deposition (ALD) method. Different thicknesses of HfO2 and Al2O3 layers (5, 10 and 20 ALD cycles) were deposited on the mesoporous TiO2 surface prior to dye loading process used for fabrication of DSSCs. It was observed that the ALD deposition of ultrathin oxides significantly improved the performance of DSSCs and that the improvement in the DSSC performance depends on the thickness of the deposited HfO2 and Al2O3 films. Compared to a reference DSSC the incorporation of a HfO2 layer resulted in 69% improvement (from 4.2 to 7.1%) in the efficiency of the cell and incorporation of Al2O3 (20 cycles) resulted in 19% improvement (from 4.2 to 5.0%) in the efficiency of the cell. These results suggest that ultrathin metal oxide layers affect the density and the distribution of interface states at the TiO2/organic dye and TiO2/liquid electrolyte interfaces and hence can be utilized to treat these interfaces in DSSCs. (C) 2009 Elsevier B.V. All rights reserved. |
| Address: | Baroughi, MF S Dakota State Univ, Dept Elect Engn |
| LINK | Teh, E. J.; Leong, Y. K.; Liu, Y. N.; Craig, V. S. J.; Walsh, R. B.; Howard, S. C. |
| "High Yield Stress Associated with Capillary Attraction between Alumina Surfaces in the Presence of Low Molecular Weight Dicarboxylic Acids" | |
| Langmuir, 2010, 26, 3067-3076 | |
| Abstract: | Adsorbed low molecular weight charged molecules are known to give rise to a range of surface forces that affect the rheological behavior of oxide dispersions. The behavior of dicarboxylic acid bolaform compounds in alumina Slurry was investigated to determine the influence of the molecular Structure oil the nanoscale interactions between alumina Surfaces and on the macroscopic properties of the slurry. The surface forces in dispersions and between a single particle and a flat surface were characterized by yield Stress and atomic force microscopy (AFM) respectively. Absorbed muconic acid increased the yield stress of the alumina system, which indicates an additional attractive interaction between the particles, Adsorbed trans,trans (TT) muconic acid resulted in a Much higher yield Stress than cis,cis (CC) muconic acid. Force-distance data obtained via AFM displayed features indicating the presence of a capillary force attraction it low pH between the alumina surfaces when TT and CC muconic acids were adsorbed at high surface coverage. This force appeared to explain the high yield stress at low pH (pH 3.6) but the absence of a net attractive force at higher pH (pH 5) did not correlate with the yield Stress results, At low pH, the muconic acids become less soluble in the confined space between the interacting surfaces resulting in the formation of an \"oily\" muconic acid phase located between the interacting surfaces. The nanosized \"oil\" phase is the source of the capillary force. |
| Address: | Craig, VSJ Australian Natl Univ, Dept Appl Math, Res Sch Phys |
| LINK | Tien, T. C.; Pan, F. M.; Wang, L. P.; Tsai, F. Y.; Lin, C. |
| "Coverage Analysis for the Core/Shell Electrode of Dye-Sensitized Solar Cells" | |
| Journal of Physical Chemistry C, 2010, 114, 10048-10053 | |
| Abstract: | In this study, we established a core/shell (C/S) model that evaluates the surface coverage of an overlayer deposited on nanoparticles in terms of X-ray photoelectron spectroscopy signals of the nanoparticles. We used the model to estimate the coverage of Al2O3 shell layers, which were deposited on the nanoporous TiO2 electrodes of dye-sensitized solar cells (DSSCs) by atomic layer deposition (ALD), as a function of the number of ALD reaction cycles. The surface coverage increased with the average thickness of the Al2O3 shell layers, indicating that the ALD Al2O3 deposition on the nanoporous electrode was via the island growth mode. The power conversion efficiency of the DSSCs was highest after the first ALD reaction cycle for the Al2O3 shell layers, which had a coverage of 0.25, according to the C/S model. The study shows that, to further improve the PCE, optimization of the ALD Al2O3 deposition condition is required so that the surface coverage of the shell layer can be increased at the first ALD reaction cycle. |
| Address: | Tien, TC Natl Chiao Tung Univ, Dept Mat Sci |
| LINK | Alessandri, I.; Depero, L. E. |
| "Metal Oxide Microrings with Femtoliter Capacity for Raman Microspectroscopy" | |
| ACS Applied Materials , 2010, 2, 594-602 | |
| Abstract: | A simple strategy, based on ultrafast heating of polystyrene microspheres infiltrated with a zinc acetate solution, is employed here for preparing ZnO microcontainers with femtoliter capacity. Their potential exploitation in micro-Raman assays for basic studies in bio- and nanotechnology is tested in different proof-of-concept experiments concerning the in situ analysis of L-glutathione crystals and gold-yeast cytochrome c bioconjugates. The ZnO microcontainers are also used as scaffolds for atomic layer deposition of TiO2 overlayers with a fine-tuning of thickness and morphology. The resulting ZnO/TiO2 heterostructures are tested in different photocatalytic experiments involving degradation and laser-induced conversion of methylene blue. |
| Address: | Alessandri, I Univ Brescia, INSTM, Via Branze 38, I-25123 Brescia, Italy Univ Brescia, INSTM, Via Branze 38, I-25123 Brescia, Italy Univ Brescia, INSTM, I-25123 Brescia, Italy Univ Brescia, Chem Technol Lab, I-25123 Brescia, Italy |
| LINK | Moriyama, N.; Ohno, Y.; Kitamura, T.; Kishimoto, S.; Mizutani, T. |
| "Change in carrier type in high-k gate carbon nanotube field-effect transistors by interface fixed charges" | |
| Nanotechnology, 2010, 21, - | |
| Abstract: | We study the phenomenon of change in carrier type in carbon nanotube field-effect transistors (CNFETs) caused by the atomic layer deposition (ALD) of a HfO2 gate insulator. When a HfO2 layer is deposited on a CNFET, the type of carrier changes from p-type to n-type. The so-obtained n-type device has good performance and stability in air. The conductivity of such a device with a channel length of 0.7 mu m is 11% of the quantum conductance 4e(2)/h. The contact resistance for electron current is estimated to be 14 k Omega. The n-type conduction of this CNFET is maintained for more than 100 days. The change in carrier type is attributed to positive fixed charges introduced at the interface between the HfO2 and SiO2 layers. We also propose a novel technique to control the type of conduction by utilizing interface fixed charges; this technique is compatible with Si CMOS process technology. |
| Address: | Ohno, Y Nagoya Univ, Dept Quantum Engn, Chikusa Ku, Furo Cho, Nagoya, Aichi 4648603, Japan Nagoya Univ, Dept Quantum Engn, Chikusa Ku, Furo Cho, Nagoya, Aichi 4648603, Japan Nagoya Univ, Dept Quantum Engn, Chikusa Ku, Nagoya, Aichi 4648603, Japan |
| LINK | Wiemer, C.; Lamagna, L.; Baldovino, S.; Perego, M.; Schamm-Chardon, S.; Coulon, P. E.; Salicio, O.; Congedo, G.; Spiga, S.; Fanciulli, M. |
| "Dielectric properties of Er-doped HfO2 (Er similar to 15%) grown by atomic layer deposition for high-kappa gate stacks" | |
| Applied Physics Letters, 2010, 96, - | |
| Abstract: | Er-doped HfO2 (Er similar to 15%) films are grown by atomic layer deposition on Si(100). The characteristics of the doped oxide are compared with those of HfO2. In Er-doped HfO2, the stabilization of the cubic structure, together with the effect of the high polarizability of Er3 , allow to obtain a dielectric constant of similar to 33 after annealing at 900 degrees C. The insertion of Er within the metallic sublattice of HfO2 reduces the net density of fixed charges, due to the creation of oxygen vacancies. For similar equivalent oxide thickness, lower leakage currents are measured for Er-doped HfO2 than for HfO2. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3400213] |
| Address: | Wiemer, C IMM CNR, Lab MDM, Via C Olivetti 2, I-20041 Agrate Brianza, Monza Brianza, Italy IMM CNR, Lab MDM, Via C Olivetti 2, I-20041 Agrate Brianza, Monza Brianza, Italy IMM CNR, Lab MDM, I-20041 Agrate Brianza, Monza Brianza, Italy Univ Milano Bicocca, Dipartimento Sci Mat, Milan, Italy Univ Toulouse, nMat Grp, F-31055 Toulouse 4, France CEMES CNRS, F-31055 Toulouse 4, France |
| LINK | Narayan, R. J.; Adiga, S. P.; Pellin, M. J.; Curtiss, L. A.; Stafslien, S.; Chisholm, B.; Monteiro-Riviere, N. A.; Brigmon, R. L.; Elam, J. W. |
| "Atomic layer deposition of nanoporous biomaterials" | |
| Materials Today, 2010, 13, 60-64 | |
| Abstract: | Due to its chemical stability, uniform pore size, and high pore density, nanoporous alumina is being investigated for use in biosensing, drug delivery, hemodialysis, and other medical applications. In recent work, we have examined the use of atomic layer deposition for coating the surfaces of nanoporous alumina membranes. Zinc oxide coatings were deposited on nanoporous alumina membranes using atomic layer deposition. The zinc oxide-coated nanoporous alumina membranes demonstrated antimicrobial activity against Escherichia coli and Staphylococcus aureus bacteria. These results suggest that atomic layer deposition is an attractive technique for modifying the surfaces of nanoporous alumina membranes and other nanostructured biomaterials. |
| Address: | Narayan, RJ Univ N Carolina, Joint Dept Biomed Engn, Raleigh, NC 27695 USA Univ N Carolina, Joint Dept Biomed Engn, Raleigh, NC 27695 USA Univ N Carolina, Joint Dept Biomed Engn, Raleigh, NC 27695 USA N Carolina State Univ, Burlington Engn Labs 2147, Raleigh, NC 27695 USA Eastman Kodak Co, Kodak Res Labs, Rochester, NY 14650 USA Argonne Natl Lab, Div Mat Sci, Argonne, IL 60439 USA N Dakota State Univ, Ctr Nanoscale Sci |
Showing customer papers 1-10 of 33 Next