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Author = Rohan, James F.;
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Displaying Results 51 - 63 of 63 on page 3 of 3
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Palladium activated self-assembled monolayer for magnetics on silicon applications
(2015)
Anthony, Ricky; Ó Mathúna, S. Cian; Rohan, James F.
Palladium activated self-assembled monolayer for magnetics on silicon applications
(2015)
Anthony, Ricky; Ó Mathúna, S. Cian; Rohan, James F.
Abstract:
Magnetic thin films such as Permalloy (Py) have been extensively used as core material in integrated power magnetic components (micro-inductors and transformers) for their excellent soft magnetic properties. Existing core electrodeposition technology requires sputtered permalloy seed layer. This seed layer etches slowly compared to the electroplated core during magnetic core patterning. In this work, a new electroless deposition process has been developed where samples are activated by palladium to realize a thin catalytic layer on SiO2. Up to 1 μm thick permalloy (∼22% ±3% Fe and ∼78%±3% Ni) is deposited from an in-house developed borane based bath to achieve ∼ 30-35 μOhm-cm resistivities. The magnetic properties of permalloy deposits reveal distinct hysteresis loop with coercivity (∼4.5 Oe). The electroless permalloy over-etch (12 μm) compared with sputtered permalloy seed is found to be negligible (2 μm). This demonstrates the applicability of permalloy electroless deposition as ...
http://hdl.handle.net/10468/7591
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Porous alumina thin films on conductive substrates for templated 1-dimensional nanostructuring
(2012)
Holubowitch, Nicolas E.; Nagle, Lorraine C.; Rohan, James F.
Porous alumina thin films on conductive substrates for templated 1-dimensional nanostructuring
(2012)
Holubowitch, Nicolas E.; Nagle, Lorraine C.; Rohan, James F.
Abstract:
The growth of thin porous anodic aluminum oxide (AAO) films on silicon by anodizing Al on Ti/Au/Si and Ti/Pt/Si substrates in oxalic acid was demonstrated. Removal of the Al2O3 barrier layer was effected by selective chemical etching in H3PO4 and a reversed bias method in the anodizing solution. Ion transport and the influence of the Ti adhesion layer at the oxide–metal interface during the critical stages of anodization and pore opening were investigated. The AAO films may be exploited as templates in the creation of silicon-integrated nanostructured wire arrays. Electrodeposition of Pt into the AAO template yielded a nanowire array with superior methanol oxidation activity that can be integrated in a micro direct methanol fuel cell.
http://hdl.handle.net/10468/1073
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Power inside - applications and technologies for integrated power in microelectronics
(2017)
Ó Mathúna, S. Cian; Kulkarni, Santosh; Pavlović, Zoran; Casey, Declan P.; Rohan, James ...
Power inside - applications and technologies for integrated power in microelectronics
(2017)
Ó Mathúna, S. Cian; Kulkarni, Santosh; Pavlović, Zoran; Casey, Declan P.; Rohan, James F.; Kelleher, Anne-Marie; Maxwell, Graeme; O'Brien, Joe; McCloskey, Paul
Abstract:
The emergence of miniaturized and integrated Power Supply on Chip (PwrSoC) and Power Supply in Package (PwrSiP) platforms will be enabled by the application of thin-film, integrated magnetics on silicon. A process flow for, and the design of, a thin-film coupled-inductor, switching at 60MHz, is described. Based on the large signal characterization data, measured up to 100MHz, the efficiency of the inductor is calculated to be 91.7% for a power of 0.5W.
http://hdl.handle.net/10468/7673
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Preparation and temperature cycling reliability of electroless Ni(P) under bump metallization
(2007)
Chen, Weimin; McCloskey, Paul; Rohan, James F.; Byrne, Patrick; McNally, Patrick J.
Preparation and temperature cycling reliability of electroless Ni(P) under bump metallization
(2007)
Chen, Weimin; McCloskey, Paul; Rohan, James F.; Byrne, Patrick; McNally, Patrick J.
Abstract:
The reliability of electroless Ni(P) under-bump metallization (UBM) was evaluated via temperature cycling and solder bump shear strength tests. Commercial diodes and dummy dies fabricated in-house were used as substrates for the electroless Ni(P) UBM deposition. Solder bumps were formed after reflowing eutectic 63Sn37Pb solder foils over the Ni(P) UBM. The solder bump shear strength was measured before and after different temperature cycling. The results from this study showed that the UBM thickness and dimension had important effects on the solder bump shear strength and reliability. Both the larger UBM dimension and larger UBM thickness tended to induce higher stress in the UBM, which resulted in the lower solder bump shear strength and lower temperature cycling reliability. A better UBM structure solution for high current electronic packaging application is indicated in this paper
http://doras.dcu.ie/189/
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Preparation and temperature cycling reliability of electroless Ni(P) under bump metallization
(2007)
Chen, Weimin; McCloskey, Paul; Rohan, James F.; Byrne, Patrick; McNally, Patrick J.
Preparation and temperature cycling reliability of electroless Ni(P) under bump metallization
(2007)
Chen, Weimin; McCloskey, Paul; Rohan, James F.; Byrne, Patrick; McNally, Patrick J.
Abstract:
The reliability of electroless Ni(P) under-bump metallization (UBM) was evaluated via temperature cycling and solder bump shear strength tests. Commercial diodes and dummy dies fabricated in-house were used as substrates for the electroless Ni(P) UBM deposition. Solder bumps were formed after reflowing eutectic 63Sn37Pb solder foils over the Ni(P) UBM. The solder bump shear strength was measured before and after different temperature cycling. The results from this study showed that the UBM thickness and dimension had important effects on the solder bump shear strength and reliability. Both the larger UBM dimension and larger UBM thickness tended to induce higher stress in the UBM, which resulted in the lower solder bump shear strength and lower temperature cycling reliability. A better UBM structure solution for high current electronic packaging application is indicated in this paper.
http://hdl.handle.net/10468/7679
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Redox cycling at interdigitated nanowire electrode arrays: enhanced electrochemical sensing
(2018)
Seymour, Ian P.; Lovera, Pierre; Wahl, Amélie J. C; Rohan, James F.; O'Riordan, Alan
Redox cycling at interdigitated nanowire electrode arrays: enhanced electrochemical sensing
(2018)
Seymour, Ian P.; Lovera, Pierre; Wahl, Amélie J. C; Rohan, James F.; O'Riordan, Alan
Abstract:
Interdigitated nanowire arrays can be used to perform generator collector type electrochemical measurements. For this set up, one comb of nanowire arrays are used to perform a standard voltammetric technique while the other comb is biased at a constant potential. This technique gives rise to multiple benefits, most notably enhancement of electrochemical signals due to redox cycling, and reduced diffusional overlap in the electrode arrays. Simulations have been used to optimize the electrode designs and to help understand the processes that occur at the electrode surfaces under these conditions. The combination of experimental and simulation data has led to the optimization of a generator collector system with significant collection efficiencies at a variety of conditions.
http://hdl.handle.net/10468/7665
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Selective electroless nickel deposition on copper as a final barrier/bonding layer material for microelectronics applications
(2001)
Rohan, James F.; O'Riordan, Gerald; Boardman, Jane
Selective electroless nickel deposition on copper as a final barrier/bonding layer material for microelectronics applications
(2001)
Rohan, James F.; O'Riordan, Gerald; Boardman, Jane
Abstract:
A low cost, selective electroless metallisation of integrated circuit (IC) copper bond pads with nickel and gold is demonstrated. This metallurgy can function as a barrier layer/bondable material when deposited as a thin layer or as the chip bump for flip chip applications when deposited to greater heights. Four alternative activation steps for selective electroless nickel deposition on bond pad copper are demonstrated. Selective low cost deposition has been achieved with a proprietary electroless plating bath developed at NMRC and three commercial baths on both sputtered copper substrates and electrolessly deposited copper on titanium nitride barrier layer material.
http://hdl.handle.net/10468/7623
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Simulations of 3D nanoscale architectures and electrolyte characteristics for Li-ion microbatteries
(2019)
Clancy, Tomás M.; Rohan, James F.
Simulations of 3D nanoscale architectures and electrolyte characteristics for Li-ion microbatteries
(2019)
Clancy, Tomás M.; Rohan, James F.
Abstract:
Finite element simulations are presented, showing material utilisation and electrochemical cell behaviour of a rechargeable Li-ion microbattery in planar thin-film, 3D and 3D core core-shell nanoarchitectures in which the active material is 250 nm thick as a shell on a 250 nm diameter core support. The materials simulated are non-porous additive-free LiCoO2, lithium metal and solid-state, polymer, polymer-gel and liquid electrolytes. The concentration profile of the LiCoO2 during discharge and areal energy versus areal power in a Ragone plot for each of the different architectures are compared. It is shown that the planar thin-film architecture gave better cell performance when used with the solid-state electrolyte with all three architectures showing material utilisation of the cathode at the closest point to the anode. The 3D and 3D core-shell nanoarchitectures show better battery performance for the polymer electrolyte then the planar thin film, with the 3D nanoarchitecture being...
http://hdl.handle.net/10468/7587
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Smart energy management and conversion
(2014)
Wang, Wensi; Rohan, James F.; Wang, Ningning; Hayes, Mike; Romani, Aldo; Macrelli, Enri...
Smart energy management and conversion
(2014)
Wang, Wensi; Rohan, James F.; Wang, Ningning; Hayes, Mike; Romani, Aldo; Macrelli, Enrico; Dini, Michele; Filippi, Matteo; Tartagni, Marco; Flandre, Denis
Abstract:
This chapter introduced power management circuits and energy storage unit designs for sub‐1 mW low power energy harvesting technologies, including indoor light energy harvesting, thermoelectric energy harvesting and vibration energy harvesting. The solutions address several of the problems associated with energy harvesting, power management and storage issues including low voltage operation, self‐start, efficiency (conversion efficiency as well as impact of power consumption of the power management circuit itself), energy density and leakage current levels. Additionally, efforts to miniaturize and integrate magnetic parts as well as integrate discrete circuits onto silicon are outlined to offer improvements in cost, size and efficiency. Finally initial results from efforts to improve energy density of storage devices using nanomaterials are introduced.
http://hdl.handle.net/10468/7702
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Sn-based micro and nano lithium battery materials
(2014)
Clancy, Tomás M.; Hasan, Maksudul; Rohan, James F.
Sn-based micro and nano lithium battery materials
(2014)
Clancy, Tomás M.; Hasan, Maksudul; Rohan, James F.
Abstract:
Energy provision and storage are significant and critical issues for wireless sensor network (WSN) applications. Hybrid energy devices incorporating energy harvesting and storage requires the development of enhanced energy storage materials and architectures. A decreased footprint with the same energy capability is desirable to maximise the energy density and enable long-life wireless sensors. Methods to structure active and support battery materials enhance the device characteristics offering mechanical and electrical support. The results below are for materials that can be processed in 3D or 1D to decrease the footprint of the energy storage element. The effect of the support material is also shown to be significant and directly relevant for high aspect ratio nanostructure where the lithium active materials experience volume changes during charge and discharge.
http://hdl.handle.net/10468/7595
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Stress modelling of multi level interconnect schemes for future deep submicron device generations
(2001)
Gonzales Montes DeOca, Carlos; Foley, Sean; Mathewson, Alan; Rohan, James F.
Stress modelling of multi level interconnect schemes for future deep submicron device generations
(2001)
Gonzales Montes DeOca, Carlos; Foley, Sean; Mathewson, Alan; Rohan, James F.
Abstract:
Copper and low dielctric constantant (k) materials are poised to become the dominant interconnect scheme for integrated circuits for the future because of the low resistance and capacitance that they offer which can improve circuit performance by more than 30% over conventional interconnect schemes. This paper addresses the thermomechanical stresses in the Cu/Low k interconnect scheme through numerical simulation and identifies the locations of maximum stress in the structure with view to providing information on the impact that different dielectric materials have on the stress distribution in the interfaces between metals and dielectric layers.
http://hdl.handle.net/10468/7692
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Ultra-fast cycling of nanoscale thin-film LiCoO2 electrodes in aqueous electrolytes
(2018)
Clancy, Tomás M.; Rohan, James F.
Ultra-fast cycling of nanoscale thin-film LiCoO2 electrodes in aqueous electrolytes
(2018)
Clancy, Tomás M.; Rohan, James F.
Abstract:
Additive‐free nanoscale LiCoO2 thin‐films deposited on Si substrates using DC sputtering show exceptional electrochemical performance due to the unique kinetics of the nanoscale thin‐film in aqueous environment. At extremely high scan rates and galvanostatic current densities of up to 100 mV s−1 and 200 C respectively, a capacity retention equivalent to 97 mAh g−1 (4.8 μAh cm−2, 48.3 μAh cm−2 μm−1) is obtained. A significant contribution of non‐diffusion controlled kinetics in a LiCoO2 electrode is shown.
http://hdl.handle.net/10468/6863
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Zincate-free, electroless nickel deposition on aluminum bond pads
(2005)
Rohan, James F.; Murphy, Patricia A.; Barrett, John
Zincate-free, electroless nickel deposition on aluminum bond pads
(2005)
Rohan, James F.; Murphy, Patricia A.; Barrett, John
Abstract:
A zincate-free electroless nickel deposition on aluminum bond pads is investigated. A three-step, etch, rinse, and electroless plating, is demonstrated for deposition on aluminum bond pads patterned with polyimide. The chemicals used are compatible with this dielectric material. The deposition has been achieved with good selectivity, uniformity, and deposition rate at 40 × 40 μ m aluminum bond pads. The adhesion and contact resistance were also determined and improved through anneals in the range 200-400°C for 1 h. The optimized condition for adhesion and contact resistance was an anneal at 400°C. The combination of a nickel hypophosphite reducing agent and the additives used leads to an active plating bath in the early stages of deposition, by comparison with commercial solutions, and hence, good coverage of the aluminum bond pad using the simplified process.
http://hdl.handle.net/10468/1363
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