Publications
200 results found
Delgado Notario JA, Javadi E, Velazquez JE, et al., 2017, Detection of terahertz radiation using submicron field effect transistors and their use for inspection applications, Conference on Millimetre Wave and Terahertz Sensors and Technology X, Publisher: SPIE-INT SOC OPTICAL ENGINEERING, ISSN: 0277-786X
Hamid A, Fobelets K, Enrique Velazquez-Perez J, 2017, Thermo-Electric Power Generators using Gated Silicon Nanowires, 11th UKSim-AMSS European Modelling Symposium on Computer Modelling and Simulation (EMS), Publisher: IEEE, Pages: 168-173, ISSN: 2473-3539
Konstantinou F, Shougee A, Albrecht T, et al., 2017, TiO2 coated Si nanowire electrodes for electrochemical double layer capacitors in room temperature ionic liquid, Journal of Physics D: Applied Physics, Vol: 50, ISSN: 0022-3727
Three TiO2 deposition processes are used to coat the surface of Si nanowire array electrodes for electrochemical double layer capacitors in the room temperature ionic liquid [Bmim][NTF2]. The fabrication processes are based on wet chemistry only and temperature treatments are kept below 450°C. Successful TiO2 coatings are found to be those that are carried out at low pressure and with low TiO2 coverage to avoid nanowires breakage. The best TiO2 coated Si nanowire array electrode in [Bmim][NTF2] showed energy densities of 0.9 Whcenterdotkg-1 and power densities of 2.2 kWcenterdotkg-1 with a nanowire length of ~10 μm.
Moser N, Panteli C, Ma D, et al., 2017, Improving the pH Sensitivity of ISFET Arrays withReactive Ion Etching, BioCAS 2017, Publisher: IEEE
In this paper, we report a method to improvesensitivity for CMOS ISFET arrays using Reactive Ion Etching(RIE) as a post-processing technique. The process etches awaythe passivation layers of the commercial CMOS process, using anoxygen (O2) and sulfur hexafluoride (SF6) plasma. The resultingattenuation and pH sensitivity are characterised for five diesetched for 0 to 15 minutes, and we demonstrate that capacitiveattenuation is reduced by 196% and pH sensitivity increasedby 260% compared to the non-etched equivalent. The spread oftrapped charge is also reduced which relaxes requirements on theanalogue front-end. The technique significantly improves the performanceof the fully-integrated sensing system for applicationssuch as DNA detection.
Delgado Notario JA, Javadi E, Clerico V, et al., 2017, Experimental and theoretical studies of Sub-THz detection using strained-Si FETs, 20th International Conference on Electron Dynamics in Semiconductors, Optoelectronics and Nanostructures (EDISON), Publisher: IOP PUBLISHING LTD, ISSN: 1742-6588
Panteli C, Georgiou P, Fobelets K, 2017, Optimising the performance of commercial ISFET sensors using Reactive Ion Etching, MNE 2017
Panteli C, Fobelets K, Sydoruk O, 2017, Graphene Suspended on Silicon Nanowire Arrays for Enhanced Gas Sensing, 231st ECS Meeting, ISSN: 2151-2043
Delgado Notario JA, Javadi E, Calvo-Gallego J, et al., 2017, Sub-Micron Gate Length Field Effect Transistors as Broad Band Detectors of Terahertz Radiation, 5th Russia-Japan-USA-Europe Symposium on Fundamental and Applied Problems of Terahertz Devices and Technologies (RJUSE-TeraTech), Publisher: WORLD SCIENTIFIC PUBL CO PTE LTD, Pages: 87-95, ISSN: 1793-1274
Panteli C, Liu D, Sydoruk O, et al., 2016, Through graphene etching of porous Si by electroless metal assisted chemical etching, MNE
Qiao L, Shougee A, Albrecht T, et al., 2016, Oxide-coated silicon nanowire array capacitor electrodes in room temperature ionic liquid, Electrochimica Acta, Vol: 210, Pages: 32-37, ISSN: 0013-4686
Improved performance of Si nanowire arrays for capacitor electrodes in ionic liquid [Bmim][NTf2], is obtained by spin-on-doping the nanowires followed by hot, concentrated nitric acid oxidation. n- and p-type Si nanowire arrays are fabricated via a 2-step metal-assisted chemical etch process to increase the effective surface area. Spin-on-doping increases the doping density of the nanowires, enhancing the current by a factor of more than 3. The well-controlled HNO3 oxidation defines a thin, dense oxide layer on the Si nanowires increasing chemical stability, both expanding the electrochemical window and increasing the current further by a factor >2. Specific capacitances of 238 μF cm−2 (∼0.4 F g−1, 159 mF cm−3) and 404 μF cm−2 (∼0.7 F g−1, 269 mF cm−3) are obtained for n- and p-type Si nanowire arrays, respectively.
shougee A, Konstantinou F, Albrecht T, et al., 2016, Silicon nanowire arrays for high capacitance electrodes in room temperature ionic liquid electrolyte, 229th ECS Meeting
Shougee A, Konstantinou F, Albrecht T, et al., 2016, Silicon nanowire arrays for high capacitance electrodes in room temperature ionic liquid electrolyte, 229th ECS Meeting
Fobelets K, 2015, Conductivity and 1/f noise in Si nanowire arrays, E-MRS spring meeting
Rahman T, Fobelets K, 2015, Efficient tool flow for 3D photovoltaic modelling, Computer Physics Communications, Vol: 193, Pages: 124-130, ISSN: 1879-2944
Performance predictions and optimisation strategies in current nanotechnology-based photovoltaic (PV) require simulation tools that can efficiently and accurately compute optical and electrical performance parameters of intricate 3D geometrical structures. Due to the complexity of each type of simulation it is often the case that a single package excels in either optical or electrical modelling, and the other remains a bottleneck. In this work, an efficient tool flow is described in order to combine the highly effective optical simulator Lumerical with the excellent fabrication and electrical simulation capability of Sentaurus. Interfacing between the two packages is achieved through tool command language and Matlab, offering a fast and accurate electro-optical characteristics of nano-structured PV devices.
Delgado-Notario JA, Meziani YM, Velazquez-Perez JE, et al., 2015, Optimization of THz response of strained-Si MODFETs, E-MRS Spring Meeting / Symposium H / Symposium I / Symposium BB / Symposium FF / Symosium D, Publisher: WILEY-V C H VERLAG GMBH, Pages: 1401-1404, ISSN: 1862-6351
- Author Web Link
- Cite
- Citations: 1
Meziani YM, Morozov S, Notario JAD, et al., 2015, Enhancement of sub-terahertz detection by drain-to-source biasing on strained silicon MODFET devices, 19th International Conference on Electron Dynamics in Semiconductors, Optoelectronics and Nanostructures (EDISON '19), Publisher: IOP PUBLISHING LTD, ISSN: 1742-6588
- Author Web Link
- Cite
- Citations: 1
Rahman T, Navarro-Cia M, Fobelets K, 2014, High density micro-pyramids with silicon nanowire array for photovoltaic applications, Nanotechnology, Vol: 25, Pages: 1-10, ISSN: 0957-4484
We use a metal assisted chemical etch process to fabricate silicon nanowire arrays (SiNWAs) onto a dense periodic array of pyramids that are formed using an alkaline etch masked with an oxide layer. The hybrid micro-nano structure acts as an anti-reflective coating with experimental reflectivity below 1% over the visible and near-infrared spectral regions. This represents an improvement of up to 11 and 14 times compared to the pyramid array and SiNWAs on bulk, respectively. In addition to the experimental work, we optically simulate the hybrid structure using a commercial finite difference time domain package. The results of the optical simulations support our experimental work, illustrating a reduced reflectivity in the hybrid structure. The nanowire array increases the absorbed carrier density within the pyramid by providing a guided transition of the refractive index along the light path from air into the silicon. Furthermore, electrical simulations which take into account surface and Auger recombination show an efficiency increase for the hybrid structure of 56% over bulk, 11% over pyramid array and 8.5% over SiNWAs.
Fobelets K, Meghani M, Li C, 2014, Influence of Minority Carrier Gas Donors on Low-Frequency Noise in Silicon Nanowires, IEEE TRANSACTIONS ON NANOTECHNOLOGY, Vol: 13, Pages: 1176-1180, ISSN: 1536-125X
- Author Web Link
- Cite
- Citations: 4
Krali E, Fobelets K, Durrani Z, 2014, Seebeck coefficient in Si nanowires and single-electron effects, Mico and Nano Engineering (MNE) 2014, Lausanne
Xu B, Fobelets K, 2014, Spin-on-doping for output power improvement of silicon nanowire array based thermoelectric power generators, Journal of Applied Physics, Vol: 115, ISSN: 0021-8979
The output power of a silicon nanowire array (NWA)-bulk thermoelectric power generator (TEG) with Cu contacts is improved by spin-on-doping (SOD). The Si NWAs used in this work are fabricated via metal assisted chemical etching (MACE) of 0.01–0.02 Ω cm resistivity n- and p-type bulk, converting ∼4% of the bulk thickness into NWs. The MACE process is adapted to ensure crystalline NWs. Current-voltage and Seebeck voltage-temperature measurements show that while SOD mainly influences the contact resistance in bulk, it influences both contact resistance and power factor in NWA-bulk based TEGs. According to our experiments, using Si NWAs in combination with SOD increases the output power by an order of 3 under the same heating power due to an increased power factor, decreased thermal conductivity of the NWA and reduced Si-Cu contact resistance.
Fobelets K, Utke I, 2014, Nano Fabrication 2013 Preface, MICROELECTRONIC ENGINEERING, Vol: 121, Pages: VII-VII, ISSN: 0167-9317
Xu B, Khouri W, Fobelets K, 2014, Two-Sided Silicon Nanowire Array/Bulk Thermoelectric Power Generator, IEEE ELECTRON DEVICE LETTERS, Vol: 35, Pages: 596-598, ISSN: 0741-3106
- Author Web Link
- Cite
- Citations: 23
Li C, Zhang C, Fobelets K, et al., 2013, Impact of ammonia on the electrical properties of <i>p</i>-type Si nanowire arrays, JOURNAL OF APPLIED PHYSICS, Vol: 114, ISSN: 0021-8979
- Author Web Link
- Cite
- Citations: 11
Li C, Fobelets K, Liu C, et al., 2013, Ag-assisted lateral etching of Si nanowires and its application to nanowire transfer, APPLIED PHYSICS LETTERS, Vol: 103, ISSN: 0003-6951
- Author Web Link
- Cite
- Citations: 9
Krali E, Li C, Fobelets K, et al., 2013, Seebeck coefficient in silicon nanowire arrays, Micro and Nanoengineering (MNE2013), London
Fobelets K, Ahmad MM, Roumyantsev S, et al., 2013, Influence of ambient on conductivity and 1/f noise in Si nanowire arrays, ICNF International Conference on Noise and Fluctuations
Fobelets K, Li CB, Coquillat D, et al., 2013, Far infrared response of silicon nanowire arrays, RSC Adv., Vol: 3, Pages: 4434-4439
The reflection, transmission and absorbance spectra of silicon nanowire arrays (NWAs), as a function of the length of the nanowires, are investigated in a wavelength range of 15 μm < λ < 200 μm, using Fourier transform infrared spectroscopy in vacuum. The NWAs are fabricated using metal-assisted electroless chemical etching. The wire length is varied between 20 μm and 140 μm, which is of the same order of magnitude as the wavelength, and their spectra are compared to bulk Si. At high frequencies the absorbance spectra of the NWAs show molecular resonances due to adsorption of molecules involved in the fabrication process but also due to the oxide quality that wraps the nanowires and changes as a function of nanowire length. Transmission characteristics show an increasing shift in absorption band edge towards the far infrared for longer wires and a transition from specular to diffuse reflection at a nanowire length of approximately 60 μm.
Meziani YM, Garcia-Garcia E, Velazquez-Perez JE, et al., 2013, Terahertz imaging using strained-Si MODFETs as sensors, Solid State Electronics, Vol: 83, Pages: 113-117
We report on non-resonant (broadband) and resonant detection of terahertz radiation using strained-Si modulation doped field effect transistors. The devices were excited at room temperature by two types of terahertz sources (an electronic source based on frequency multipliers at 0.292 THz and a pulsed parametric laser at 1.5 THz). In both cases, a non-resonant response with maxima around the threshold voltage was observed. Shubnikov-de Haas and photoresponse measurements were performed simultaneously and showed a phase-shift of π/2 in good agreement with the theory, which demonstrates that the observed response is related to the plasma waves oscillation in the channel. The non-resonant features were used to demonstrate the capabilities of such devices in terahertz imaging. We also cooled our device down to 4.2 K to increase the quality factor and resonant detection was observed by using a tunable source of terahertz radiation.
Meziani YM, Garcia-Garcia E, Velazquez-Perez JE, et al., 2013, Terahertz detection using Si-SiGe MODFETs, Spanish Conference on Electron Devices (CDE), Pages: 167-170
Rahman T, Fobelets K, 2013, Simulation of Rough Silicon Nanowire Array for use in Spin-On-Doped PN core-shell Solar Cells, UKSim-AMSS 7th European Modelling Symposium on Computer Modelling and Simulation (EMS), Publisher: IEEE, Pages: 725-729, ISSN: 2473-3539
- Author Web Link
- Cite
- Citations: 1
This data is extracted from the Web of Science and reproduced under a licence from Thomson Reuters. You may not copy or re-distribute this data in whole or in part without the written consent of the Science business of Thomson Reuters.