| 1. |
- Zhu, Zhongyunshen, et al.
(författare)
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Performance enhancement of GaSb vertical nanowire p-type MOSFETs on Si by rapid thermal annealing
- 2022
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Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 33:7
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Tidskriftsartikel (refereegranskat)abstract
- GaSb is considered as an attractive p-type channel material for future III-V metal-oxide-semiconductor (MOS) technologies, but the processing conditions to utilize the full device potential such as low power logic applications and RF applications still need attention. In this work, applying rapid thermal annealing (RTA) to nanoscale GaSb vertical nanowire p-type MOS field-effect transistors, we have improved the average peak transconductance (g m,peak) by 50% among 28 devices and achieved 70 μS μm-1 at V DS = -0.5 V in a device with 200 nm gate length. In addition, a low subthreshold swing down to 144 mV dec-1 as well as an off-current below 5 nA μm-1 which refers to the off-current specification in low-operation-power condition has been obtained. Based on the statistical analysis, the results show a great enhancement in both on- and off-state performance with respect to previous work mainly due to the improved electrostatics and contacts after RTA, leading to a potential in low-power logic applications. We have also examined a short channel device with L g = 80 nm in RTA, which shows an increased g m,peak up to 149 μS μm-1 at V DS = -0.5 V as well as a low on-resistance of 4.7 kΩ•μm. The potential of further enhancement in g m via RTA offers a good alternative to obtain high-performance devices for RF applications which have less stringent requirement for off-state performance. Our results indicate that post-fabrication annealing provides a great option to improve the performance of GaSb-based p-type devices with different structures for various applications.
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| 2. |
- Löfstrand, Anette, et al.
(författare)
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Feature size control using surface reconstruction temperature in block copolymer lithography for InAs nanowire growth
- 2020
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Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 31:32
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Tidskriftsartikel (refereegranskat)abstract
- Here we present a method to control the size of the openings in hexagonally organized BCP thin films of poly(styrene)-block-poly(4-vinylpyridine) (PS-b-P4VP) by using surface reconstruction. The surface reconstruction is based on selective swelling of the P4VP block in ethanol, and its extraction to the surface of the film, resulting in pores upon drying. We found that the BCP pore diameter increases with ethanol immersion temperature. In our case, the temperature range 18 to 60 °C allowed fine-Tuning of the pore size between 14 and 22 nm. A conclusion is that even though the molecular weight of the respective polymer blocks is fixed, the PS-b-P4VP pore diameter can be tuned by controlling temperature during surface reconstruction. These results can be used for BCP-based nanofabrication in general, and for vertical nanowire growth in particular, where high pattern density and diameter control are of importance. Finally, we demonstrate successful growth of indium arsenide InAs vertical nanowires by selective-Area metal-organic vapor phase epitaxy (MOVPE), using a silicon nitride mask patterned by the proposed PS-b-P4VP surface reconstruction lithography method.
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| 3. |
- Memisevic, Elvedin, et al.
(författare)
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Impact of source doping on the performance of vertical InAs/InGaAsSb/GaSb nanowire Tunnel Field-Effect Transistors
- 2018
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Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 29:43
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we analyze experimental data from state-of-the-art vertical InAs/InGaAsSb/GaSb nanowire Tunnel Field-Effect Transistors to study influence of the source doping on their performance. Overall, the doping level impacts both off-state and on-state performance of these devices. Separation of the doping from the heterostructure improved the subthreshod swing of the devices. Best devices reached a point subthreshold swing of 30 mV/dec at 100x higher currents than what Si-based TFETs has achieved previously. However, separation of doping from the heterostructure had a significant impact on the on-state performance of these devices due to effects related to source depletion. Increase of the doping level, helped to improve the on-state performance, which also increased the subthreshold swing. Thus, further optimization of doping incorporation at the heterostructure will help to improve vertical InAs/InGaAsSb/GaSb nanowire TFETs.
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| 4. |
- 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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| 5. |
- Borg, Mattias, et al.
(författare)
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Synthesis and properties of antimonide nanowires
- 2013
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Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 24:20
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Forskningsöversikt (refereegranskat)abstract
- Antimonide semiconductors are suitable for low-power electronics and long-wavelength optoelectronic applications. In recent years research on antimonide nanowires has become a rapidly growing field, and nano-materials have promising applications in fundamental physics research, for tunnel field-effect transistors, and long-wavelength detectors. In this review, we give an overview of the field of antimonide nanowires, beginning with a description of the synthesis of these nano-materials. Here we summarize numerous reports on antimonide nanowire growth, with the aim to give an overall picture of the distinctive properties of antimonide nanowire synthesis. Secondly, we review the data on the physical properties and emerging applications for antimonide nanowires, focusing on applications in electronics and optics.
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| 6. |
- Caroff, Philippe, et al.
(författare)
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InSb heterostructure nanowires: MOVPE growth under extreme lattice mismatch.
- 2009
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Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 20:49
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate the growth of InSb-based nanowire heterostructures by metalorganic vapour phase epitaxy and use it to integrate InSb on extremely lattice-mismatched III-V nanowire templates made of InAs, InP, and GaAs. Influence of temperature, V/III ratio, and diameter are investigated in order to investigate the growth rate and morphology. The range of growth temperatures used for InSb nanowire growth is very similar to that used for planar growth due to the nature of the precursor decomposition. This makes optimization of growth parameters very important, and more difficult than for most other nanowire III-V materials. Analysis of the InSb nanowire epitaxial quality when grown on InAs, InP, and GaAs, along with InSb segment and particle compositions are reported. This successful direct integration of InSb nanowires, on nanowire templates with unprecedented strain levels show great promise for fabrication of vertical InSb devices.
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| 7. |
- Ganjipour, Bahram, et al.
(författare)
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Electrical properties of GaSb/InAsSb core/shell nanowires
- 2014
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Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 25:42
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Tidskriftsartikel (refereegranskat)abstract
- Temperature dependent electronic properties of GaSb/InAsSb core/shell and GaSb nanowires have been studied. Results from two-probe and four-probe measurements are compared to distinguish between extrinsic (contact-related) and intrinsic (nanowire) properties. It is found that a thin (2-3 nm) InAsSb shell allows low barrier charge carrier injection to the GaSb core, and that the presence of the shell also improves intrinsic nanowire mobility and conductance in comparison to bare GaSb nanowires. Maximum intrinsic field effect mobilities of 200 and 42 cm(2) Vs(-1) were extracted for the GaSb/InAsSb core/shell and bare-GaSb NWs at room temperature, respectively. The temperature-dependence of the mobility suggests that ionized impurity scattering is the dominant scattering mechanism in bare GaSb while phonon scattering dominates in core/shell nanowires. Top-gated field effect transistors were fabricated based on radial GaSb/InAsSb heterostructure nanowires with shell thicknesses in the range 5-7 nm. The fabricated devices exhibited ambipolar conduction, where the output current was studied as a function of AC gate voltage and frequency. Frequency doubling was experimentally demonstrated up to 20 kHz. The maximum operating frequency was limited by parasitic capacitance associated with the measurement chip geometry.
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| 8. |
- Gorji, Sepideh, et al.
(författare)
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Growth of InAs/InP core-shell nanowires with various pure crystal structures.
- 2012
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Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 23:28
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Tidskriftsartikel (refereegranskat)abstract
- We have studied the epitaxial growth of an InP shell on various pure InAs core nanowire crystal structures by metal-organic vapor phase epitaxy. The InP shell is grown on wurtzite (WZ), zinc-blende (ZB), and {111}- and {110}-type faceted ZB twin-plane superlattice (TSL) structures by tuning the InP shell growth parameters and controlling the shell thickness. The growth results, particularly on the WZ nanowires, show that homogeneous InP shell growth is promoted at relatively high temperatures (∼500 °C), but that the InAs nanowires decompose under the applied conditions. In order to protect the InAs core nanowires from decomposition, a short protective InP segment is first grown axially at lower temperatures (420-460 °C), before commencing the radial growth at a higher temperature. Further studies revealed that the InP radial growth rate is significantly higher on the ZB and TSL nanowires compared to WZ counterparts, and shows a strong anisotropy in polar directions. As a result, thin shells were obtained during low temperature InP growth on ZB structures, while a higher temperature was used to obtain uniform thick shells. In addition, a schematic growth model is suggested to explain the basic processes occurring during the shell growth on the TSL crystal structures.
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| 9. |
- Gorji, Sepideh, et al.
(författare)
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Uniform and position-controlled InAs nanowires on 2('') Si substrates for transistor applications.
- 2012
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Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 23:1
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Tidskriftsartikel (refereegranskat)abstract
- This study presents a novel approach for indirect integration of InAs nanowires on 2('') Si substrates. We have investigated and developed epitaxial growth of InAs nanowires on 2('') Si substrates via the introduction of a thin yet high-quality InAs epitaxial layer grown by metalorganic vapor phase epitaxy. We demonstrate well-aligned nanowire growth including precise position and diameter control across the full wafer using very thin epitaxial layers (<300 nm). Statistical analysis results performed on the grown nanowires across the 2('') wafer size verifies our full control on the grown nanowire with 100% growth yield. From the crystallographic viewpoint, these InAs nanowires are predominantly of wurtzite structure. Furthermore, we show one possible device application of the aforementioned structure in vertical wrap-gated field-effect transistor geometry. The vertically aligned InAs nanowires are utilized as transistor channels and the InAs epitaxial layer is employed as the source contact. A high uniformity of the device characteristics for numerous transistors is further presented and RF characterization of these devices demonstrates an f(t) of 9.8 GHz.
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| 10. |
- Karlström, Olov, et al.
(författare)
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Analysing the capacitance–voltage measurements of vertical wrapped-gated nanowires
- 2008
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Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 19:43
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Tidskriftsartikel (refereegranskat)abstract
- The capacitance of arrays of vertical wrapped-gate InAs nanowires is analysed. With the help of a Poisson–Schrödinger solver, information about the doping density can be obtained directly. Further features in the measured capacitance–voltage characteristics can be attributed to the presence of surface states as well as the coexistence of electrons and holes in the wire. For both scenarios, quantitative estimates are provided. It is furthermore shown that the difference between the actual capacitance and the geometrical limit is quite large, and depends strongly on the nanowire material.
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