| 1. |
- Adolfsson, Karl, et al.
(författare)
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Fluorescent Nanowire Heterostructures as a Versatile Tool for Biology Applications
- 2013
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 13:10, s. 4728-4732
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Tidskriftsartikel (refereegranskat)abstract
- Nanowires are increasingly used in biology, as sensors, as injection devices, and us model systems for toxicity studies. Currently, in situ visualization of nanowires in biological media is done using organic dyes, which a;:e prone to photobleaching, or using microscopy methods which either yield poor resolution or require a sophisticated setup. Here we show that inherently fluorescent nanowire axial heterostructnies c:an be used to localize and identify nanowires in cells and tissue; By synthesizing GaP GaInP nanowire heterostructures, with nonfluorescent GaP segments and fluorescent GaInP segments, we created a barcode labeling system enabling the distinction of the nanowire morphological and chemical properties using fluorescence microscopy. The GaInP photoluminescence stability, combined with the fact that the nanowires can be coated with different materials while retaining their fluorescence, make these nanowires promising tools for biological and nanotoxicological studies.
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| 2. |
- Berg, Martin, et al.
(författare)
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InAs nanowire MOSFETs in three-transistor configurations: single balanced RF down-conversion mixers.
- 2014
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Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 25:48
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Tidskriftsartikel (refereegranskat)abstract
- Integration of III-V semiconductors on Si substrates allows for the realization of high-performance, low power III-V electronics on the Si-platform. In this work, we demonstrate the implementation of single balanced down-conversion mixer circuits, fabricated using vertically aligned InAs nanowire devices on Si. A thin, highly doped InAs buffer layer has been introduced to reduce the access resistance and serve as a bottom electrode. Low-frequency voltage conversion gain is measured up to 7 dB for a supply voltage of 1.5V. Operation of these mixers extends into the GHz regime with a [Formula: see text] cut-off frequency of 2 GHz, limited by the optical lithography system used. The circuit dc power consumption is measured at 3.9 mW.
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| 3. |
- Berg, Martin, et al.
(författare)
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Single Balanced Down-Conversion Mixer Utilizing Indium Arsenide Nanowire MOSFETs
- 2014
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Ingår i: 26th International Conference on Indium Phosphideand Related Materials (IPRM). - 1092-8669.
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Konferensbidrag (refereegranskat)abstract
- We have fabricated single balanced down-conversion mixer circuits using InAs nanowire MOSFETs as both active and passive devices. This is achieved by a combination of electron beam lithography and UV-lithography with a line width of 12 mu m. The circuits exhibit a low frequency voltage conversion gain of 6 dB, a -3 dB cutoff frequency of 2 GHz and a power consumption of 3.8 mW, while operating at a supply voltage of 1.5 V. The circuits retain circuit functionality even for a supply voltage of 1 V.
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| 4. |
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| 5. |
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| 6. |
- Egard, Mikael, et al.
(författare)
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High-Frequency Performance of Self-Aligned Gate-Last Surface Channel In0.53Ga0.47As MOSFET
- 2012
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Ingår i: IEEE Electron Device Letters. - 0741-3106. ; 33:3, s. 369-371
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Tidskriftsartikel (refereegranskat)abstract
- We have developed a self-aligned L-g = 55 nm In-0.53 Ga-0.47 As MOSFET incorporating metal-organic chemical vapor deposition regrown n(++) In0.6Ga0.4As source and drain regions, which enables a record low on-resistance of 199 Omega mu m. The regrowth process includes an InP support layer, which is later removed selectively to the n(++) contact layer. This process forms a high-frequency compatible device using a low-complexity fabrication scheme. We report on high-frequency measurements showing f(max) of 292 GHz and f(t) of 244 GHz. These results are accompanied by modeling of the device, which accounts for the frequency response of gate oxide border traps and impact ionization phenomenon found in narrow band gap FETs. The device also shows a high drive current of 2.0 mA/mu m and a high extrinsic transconductance of 1.9 mS/mu m. These excellent properties are attributed to the use of a gate-last process, which does not include high temperature or dry-etch processes.
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| 7. |
- Egard, Mikael, et al.
(författare)
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Vertical InAs nanowire wrap gate transistors with f(t) > 7 GHz and f(max) > 20 GHz.
- 2010
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 10:3, s. 809-812
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Tidskriftsartikel (refereegranskat)abstract
- In this letter we report on high-frequency measurements on vertically standing III-V nanowire wrap-gate MOSFETs (metal-oxide-semiconductor field-effect transistors). The nanowire transistors are fabricated from InAs nanowires that are epitaxially grown on a semi-insulating InP substrate. All three terminals of the MOSFETs are defined by wrap around contacts. This makes it possible to perform high-frequency measurements on the vertical InAs MOSFETs. We present S-parameter measurements performed on a matrix consisting of 70 InAs nanowire MOSFETs, which have a gate length of about 100 nm. The highest unity current gain cutoff frequency, f(t), extracted from these measurements is 7.4 GHz and the maximum frequency of oscillation, f(max), is higher than 20 GHz. This demonstrates that this is a viable technique for fabricating high-frequency integrated circuits consisting of vertical nanowires.
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| 8. |
- Gomez-Carretero, Salvador, et al.
(författare)
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Salmonella Biofilm Modulation with Electrically Conducting Polymers
- 2014
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Biofilms are ubiquitous in many human activities, constituting a threat or an advantage depending on the context of application. It is therefore of great interest to obtain new materials to study and control how biofilms are formed. Here, heparin and DBS (dodecylbenzenesulfonate) are incorporated as counter-ions to the PEDOT (poly(3,4-ethylenedioxythiophene)) backbone, forming conducting polymer thin-films. Polymer synthesis is based on electrodeposition, allowing for the adjustment, during fabrication, of properties like charge and hydrophobicity, important in bacterial adhesion. The electrochemical redox state of the polymer is of fundamental importance in Salmonella enterica Serovar Typhimurium biofilm modulation. Oxidized composites show increased levels of biofilm growth compared to reduced and pristine polymer films. As a result, biofilm formation is modulated by the application of a low electric voltage. Moreover, biofilm morphology and topology are affected by both the electrochemical redox state and the incorporated counter-ion, making these materials a useful tool in biofilm engineering.
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| 9. |
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| 10. |
- Lind, Erik, et al.
(författare)
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High Frequency Performance of Vertical InAs Nanowire MOSFET
- 2010
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Ingår i: 2010 22Nd International Conference On Indium Phosphide And Related Materials (Iprm). - 1092-8669. - 9781424459193
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Konferensbidrag (refereegranskat)abstract
- We report on RF characterization of vertical, 100-nm-gate length InAs nanowire MOSFETs, utilizing wrap-gate technology and Al2O3 high-kappa gate oxide. The transistors show f(t)=5.6 GHz and f(max)=22 GHz, mainly limited by parasitic capacitances. The RF device performance is described using a hybrid-pi model taking hole generation at the drain into account. Electrostatic modeling of the parasitic capacitances for arrays of vertical nanowires indicates that a strong reduction in extrinsic capacitances can be achieved for devices with a small inter-wire separation.
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| 11. |
- Persson, Karl-Magnus, et al.
(författare)
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1/f-noise in Vertical InAs Nanowire Transistors
- 2013
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Ingår i: 2013 International Conference on Indium Phosphide and Related Materials (IPRM). - 1092-8669. ; , s. 1-2
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Konferensbidrag (refereegranskat)abstract
- The material quality at high-k interfaces are a major concern for FET devices. We study the effect on two types of InAs nanowire (NW) transistors and compare their characteristics. It is found that by introducing an inner layer of Al2O3 at the high-kappa interface, the low frequency noise (LFN) performance regarding gate voltage noise spectral density, S-Vg, is improved by one order of magnitude per unit gate area.
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| 12. |
- Persson, Kristin M, et al.
(författare)
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Electronic control of cell detachment using a self-doped conducting polymer
- 2011
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Ingår i: Advanced Materials. - : Wiley-Blackwell. - 0935-9648 .- 1521-4095. ; 23:38, s. 4403-4408
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Tidskriftsartikel (refereegranskat)abstract
- An electronic detachment technology based on thin films of a poly(3,4-ethylene-dioxythiophene) derivative is evaluated for controlled release of human epithelial cells. When applying a potential of 1 V, the redox-responsive polymer films detach and disintegrate and at the same time release cells cultured on top in the absence of any enzymatic treatment with excellent preservation of membrane proteins and cell viability.
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| 13. |
- Persson, Karl-Magnus, et al.
(författare)
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Extrinsic and Intrinsic Performance of Vertical InAs Nanowire MOSFETs on Si Substrates
- 2013
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Ingår i: IEEE Transactions on Electron Devices. - 0018-9383. ; 60:9, s. 2761-2767
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents DC and RF characterization as well as modeling of vertical InAs nanowire MOSFETs with LG = 200 nm and Al2O3/HfO2 high-κ dielectric. Measurements at VDS = 0.5 V show that high transconductance (gm = 1.37 mS/μm), high drive current (IDS = 1.34 mA/μm), and low on-resistance (RON = 287 Ωμm) can be realized using vertical InAs nanowires on Si substrates. By measuring the 1/f-noise, the gate area normalized gate voltage noise spectral density, SVG·LG·WG, is determined to be lowered one order of magnitude compared to similar devices with a high-κ film consisting of HfO2 only. Additionally, with a virtual source model we are able to determine the intrinsic transport properties. These devices (LG = 200 nm) show a high injection velocity (vinj = 1.7·107 cm/s) with a performance degradation for array FETs predominantly due to an increase in series resistance.
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| 14. |
- Persson, Karl-Magnus, et al.
(författare)
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InAs nanowire MOSFET differential active mixer on Si-substrate
- 2014
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Ingår i: Electronics Letters. - : Institution of Engineering and Technology (IET). - 1350-911X .- 0013-5194. ; 50:9, s. 682-682
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Tidskriftsartikel (refereegranskat)abstract
- An active single balanced down-conversion mixer is implemented using InAs nanowire metal oxide semiconductor field effect transistors (MOSFETs) as both active devices and passive resistive loads. Circuits with 6 dB low-frequency voltage gain and a 3 dB bandwidth of 2 GHz are measured for a DC power consumption of 3.8 mW from a 1.5 V supply. The circuits are fabricated using contacts made with 12 μmline- width optical lithography.
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| 15. |
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| 16. |
- Persson, Karl-Magnus, et al.
(författare)
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Low-frequency noise in vertical InAs nanowire FETs
- 2010
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Ingår i: IEEE Electron Device Letters. - 0741-3106. ; 31:5, s. 428-430
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Tidskriftsartikel (refereegranskat)abstract
- This letter presents dc characteristics and low-frequency noise (LFN) measurements on single vertical InAs nanowire MOSFETs with 35-nm gate length and HfO2 high-kappa dielectric. The average normalized transconductance for three devices is 0.16 S/mm, with a subthreshold slope of 130 mV/decade. At 10 Hz, the normalized noise power S-I/I-d(2) measures 7.3 x 10(-7) Hz(-1). Moreover, the material-dependent Hooge's parameter at room temperature is estimated to be 4.2 x 10(-3).
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| 17. |
- Persson, Karl-Magnus
(författare)
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Nanowire Transistors and RF Circuits for Low-Power Applications
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The background of this thesis is related to the steadily increasing demand of higher bandwidth and lower power consumption for transmitting data. The work aims at demonstrating how new types of structures, at the nanoscale, combined with what is referred to as exotic materials, can help benefit in electronics by lowering the consumed power, possibly by an order of magnitude, compared to the industry standard, silicon (Si), used today. Nanowires are semiconductor rods, with two dimensions at the nanoscale, which can be either grown with a bottom-up technique, or etched out with a top-down approach. The research interest concerning nanowires has gradually increasing for over two decades. Today, few have doubts that nanowires represent an attractive alternative, as scaling of planar structures has reached fundamental limits. With the enhanced electrostatics of a surrounding gate, nanowires offer the possibility of continued miniaturization, giving semiconductors a prolonged window of performance improvements. As a material choice, compound semiconductors with elements from group III and V (III-Vs), such as indium arsenide (InAs), have the possibility to dramatically decrease power consumption. The reason is the inherent electron transport properties of III-Vs, where an electron can travel, in the order of, 10 times faster than in Si. In the projected future, inclusion of III-Vs, as an extension to the Si-CMOS platform, seems almost inevitable, with many of the largest electronics manufacturing companies showing great interest. To investigate the technology potential, we have fabricated InAs nanowire metal-oxide-semiconductor field effect transistors (NW-FETs). The performance has been evaluated measuring both RF and DC characteristics. The best devices show a transconductance of 1.36 mS/µm (a device with a single nanowire, normalized to the nanowire circumference) and a maximum unilateral power gain at 57 GHz (for a device with several parallel nanowires), both values at a drive voltage of 0.5 V. The performance metrics are found to be limited by the capacitive load of the contact pads as well as the resistance in the non-gated segments of the nanowires. Using computer models, we have also been able to extract intrinsic transport properties, quantifying the velocity of charge carrier injection, which is the limiting property of semi-ballistic and ballistic devices. The value for our 45-nm-in-diameter nanowires, with 200 nm channel length, is determined to 1.7∙107 cm/s, comparable to other state-of-the-art devices at the same channel length. To demonstrate a higher level of functionality, we have connected several NW-FETs in a circuit. The fabricated circuit is a single balanced differential direct conversion mixer and is composed of three stages; transconductance, mixing, and transimpedance. The basic idea of the mixer circuit is that an information signal can either be extracted from or inserted into a carrier wave at a higher frequency than the information wave itself. It is the relative size of the first and the third stage that accounts for the circuit conversion gain. Measured circuits show a voltage conversion gain of 6 dB and a 3-dB bandwidth of 2 GHz. A conversion mixer is a vital component when building a transceiver, like those found in a cellphone and any other type of radio signal transmitting device. For all types of signals, noise imposes a fundamental limitation on the minimal, distinguishable amplitude. As transistors are scaled down, fewer carriers are involved in charge transport, and the impact of frequency dependent low-frequency noise gets relatively larger. Aiming towards low power applications, it is thus of importance to minimize the amount of transistor generated noise. Included in the thesis are studies of the level and origin of low-frequency 1/f-noise generated in NW-FETs. The measured noise spectral density is comparable to other non-planar devices, including those fabricated in Si. The data suggest that the level of generated noise can be substantially lowered by improving the high-k dielectric film quality and the channel interface. One significant discovery is that the part of the noise originating from the bulk nanowire, identified as mobility fluctuations, is comparably much lower than the measured noise level related to the nanowire surface. This result is promising as mobility fluctuations set the lower limit of what is achievable within a material system.
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| 18. |
- Persson, Karl-Magnus, et al.
(författare)
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Surface and core contribution to 1/f-noise in InAs nanowire metal-oxide-semiconductor field-effect transistors
- 2013
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 103:3
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Tidskriftsartikel (refereegranskat)abstract
- By measuring 1/f-noise in wrap-gated InAs nanowire metal-oxide-semiconductor field-effect transistors with transport dominating, controllably, in either an inner, core channel, or an outer, surface channel, it is possible to accurately evaluate the material quality related Hooge-parameter, alpha(H), with reduced interference from the surface properties. The devices show low values of alpha(H) similar to 4 x 10(-5). At forward bias, where the data suggest that the 1/f-noise is dominated by the contribution from the high-k interface, devices show low values of normalized noise spectral density. (C) 2013 AIP Publishing LLC.
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| 19. |
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| 20. |
- Wallentin, Jesper, et al.
(författare)
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Hard X-ray Detection Using a Single nm Diameter Nanowire
- 2014
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 14:12, s. 7071-7076
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Tidskriftsartikel (refereegranskat)abstract
- Submicron sized sensors could allow higher resolution in X-ray imaging and diffraction measurements, which are ubiquitous for materials science and medicine. We present electrical measurements of a single 100 nm diameter InP nanowire transistor exposed to hard X-rays. The X-ray induced conductance is over 5 orders of magnitude larger than expected from reported data for X-ray absorption and carrier lifetimes. Time-resolved measurements show very long characteristic lifetimes on the order of seconds, tentatively attributed to long-lived traps, which give a strong amplification effect. As a proof of concept, we use the nanowire to directly image an X-ray nanofocus with submicron resolution.
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