| 41. |
- Borgström, Magnus, et al.
(författare)
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Site-control of InAs quantum dots on a patterned InP surface: As/P exchange reactions
- 2002
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Ingår i: 7th International Conference on Nanometer-Scale Science and Technology and 21st European Conference on Surface Science.
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Konferensbidrag (refereegranskat)abstract
- We present the effect of annealing temperature and annealing time on InAs/InP site-controlled quantum dot growth. Electron beam pre-patterning forms carbon nano-deposits at the InP surface, which then can be used as growth masks to form nano-holes at the surface. By only annealing of the patterned InP surface under an arsine ambient, As/P exchange reactions produce material sufficient for selective dot nucleation in the holes at the surface
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| 42. |
- Bryllert, Tomas, et al.
(författare)
-
Designed emitter states in resonant tunneling through quantum dots
- 2002
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 80:15, s. 2681-2683
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Tidskriftsartikel (refereegranskat)abstract
- Resonant tunneling through a single layer of self-assembled quantum dots (QDs) is compared to tunneling through two layers of vertically aligned (stacked) dots. The difference can be viewed as going from a two-dimensional emitter to a zero-dimensional emitter. The temperature dependence of current peaks originating in tunneling through individual QDs and individual stacks is used to clarify this point. In addition, we show that the statistical size distribution of self-assembled quantum dots causing the inhomogeneous broadening in luminescence experiments can be analyzed in a resonant tunneling experiment. (C) 2002 American Institute of Physics.
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| 43. |
- Bryllert, Tomas, et al.
(författare)
-
Resonant tunneling through coupled self-assembled quantum dots and the influence of inhomogeneous broadening
- 2002
-
Ingår i: 7th International Conference on Nanometer-Scale Science and Technology and 21st European Conference on Surface Science.
-
Konferensbidrag (refereegranskat)abstract
- Resonant tunneling through a single layer of self-assembled quantum dots (QDs) as well as tunneling through two layers of vertically aligned (stacked) dots is investigated. The difference between single and double layers of QDs can be viewed as going from a two-dimensional emitter to a zero-dimensional emitter. By fabricating small-area devices we are able to probe single stacks of quantum dots, revealing details of the coupling between the stacked dots. Very sharp resonances, with peak-to-valley ratios of several hundred, have been measured in the current-voltage characteristics. We also show that the statistical size distribution of self-assembled quantum dots causing the inhomogeneous broadening in luminescence experiments can be analysed in a resonant tunneling experiment
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| 44. |
- Bryllert, Tomas, et al.
(författare)
-
Transport through an isolated artificial molecule formed from stacked self-assembled quantum dots
- 2003
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 82:16, s. 2655-2657
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Tidskriftsartikel (refereegranskat)abstract
- We investigate resonant tunneling through two coupled self-assembled quantum dots. The strong confinement and the high crystalline quality provided by the self-assembled dots, in combination with the tunneling coupling between the dots, create a system that may be thought of as an artificial molecule. We are able to isolate one single artificial molecule and detailed investigations of the electrical properties are performed. Peak-to-valley ratios above 1000 and full width half maximum of a few millivolts are measured at 4 K. By changing the temperature we also observe Coulomb blockade effects in a different way. (C) 2003 American Institute of Physics.
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| 45. |
- Bryllert, Tomas, et al.
(författare)
-
Vertical high-mobility wrap-gated InAs nanowire transistor
- 2006
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Ingår i: IEEE Electron Device Letters. - 0741-3106 .- 1558-0563. ; 27:5, s. 323-325
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Tidskriftsartikel (refereegranskat)abstract
- In this letter, the authors demonstrate a vertical wrap-gated field-effect transistor based on InAs nanowires [Proc. DRC, 2005, p. 157]. The nanowires have a diameter of 80 nm and are grown using selective epitaxy; a matrix of typically 10 x 10 vertically standing wires is used as channel in the transistor. The authors measure current saturation at V-ds = 0.15 V (V-g = 0 V), and a high mobility, compared to the previous nanowire transistors, is deduced.
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| 46. |
- Bryllert, Tomas, et al.
(författare)
-
Vertical high mobility wrap-gated InAs nanowire transistor
- 2005
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Ingår i: 63rd Device Research Conference Digest, 2005. DRC '05. - 0780390407 ; 1
-
Konferensbidrag (refereegranskat)abstract
- We demonstrate a wrap-gated field effect transistor based on a matrix of vertically standing InAs nanowires (Jensen, et. al., 2004). A lower limit of the mobility, derived from the transconductance, is on the order of 3000 cm2/Vs. The narrow ~100 nm channels show excellent current saturation and a threshold of Vg = -0.15 V. The sub-threshold characteristics show a close to ideal slope of 62mV/decade over two orders of magnitude
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| 47. |
- Bryllert, Tomas, et al.
(författare)
-
Vertical wrap-gated nanowire transistors
- 2006
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Ingår i: Nanotechnology. - 0957-4484. ; 17:11, s. 227-230
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Tidskriftsartikel (refereegranskat)abstract
- We present a process for fabricating a field-effect transistor based on vertically standing InAs nanowires and demonstrate initial device characteristics. The wires are grown by chemical beam epitaxy at lithographically defined locations. Wrap gates are formed around the base of the wires through a number of deposition and etch steps. The fabrication is based on standard III - V processing and includes no random elements or single nanowire manipulation.
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| 48. |
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| 49. |
- Dey, Anil, et al.
(författare)
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15 nm diameter InAs nanowire MOSFETs
- 2011
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Ingår i: [Host publication title missing]. - 1548-3770. ; , s. 21-22
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Konferensbidrag (refereegranskat)abstract
- InAs is an attractive channel material for III–V nanowire MOSFETs and early prototype high performance nanowire transistors have been demonstrated1. As the gate length is reduced, the nanowire diameter must be scaled quite aggressively in order to suppress short-channel effects2. However, a reduction in transconductance (gm) and drive current (ION) could be expected due to increased surface scattering for thin wires. We present data for the device properties of thin InAs nanowires, with diameters in the 15 nm range, and investigate possible improvements of the performance focusing on transistor applications. In order to boost ION, the source and drain resistance need to be reduced. Several doping sources were therefore evaluated in the study, among them selenium (Se), tin (Sn) and sulphur (S) to form n-i-n structures. We report very high current densities, up to 33 MA/cm2, comparable to modern HEMTs3, and a normalized transconductance of 1.8 S/mm for a nanowire with an intrinsic segment of nominally 150 nm and a diameter of 15 nm.
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| 50. |
- Dey, Anil, et al.
(författare)
-
Combining axial and radial nanowire heterostructures: Radial Esaki diodes and tunnel field-effect transistors
- 2013
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 13:12, s. 5919-5924
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Tidskriftsartikel (refereegranskat)abstract
- The ever-growing demand on high-performance electronics has generated transistors with very impressive figures of merit. The continued scaling of the supply voltage of field-effect transistors, such as tunnel field-effect transistors (TFETs), requires the implementation of advanced transistor architectures including FinFETs and nanowire devices. Moreover, integration of novel materials with high electron mobilities, such as III-V semiconductors and graphene, are also being considered to further enhance the device properties. In nanowire devices, boosting the drive current at a fixed supply voltage or maintaining a constant drive current at a reduced supply voltage may be achieved by increasing the cross-sectional area of a device, however at the cost of deteriorated electrostatics. A gate-all-around nanowire device architecture is the most favorable electrostatic configuration to suppress short channel effects, however, the arrangement of arrays of parallel vertical nanowires to address the drive current predicament will require additional chip area. The use of a core-shell nanowire with a radial heterojunction in a transistor architecture provides an attractive means to address the drive current issue without compromising neither chip area nor device electrostatics. In addition to design advantages of a radial transistor architecture, we in this work illustrate the benefit in terms of drive current per unit chip area and compare the experimental data for axial GaSb/InAs Esaki diodes and TFETs to their radial counterparts and normalize the electrical data to the largest cross-sectional area of the nanowire, i.e. the occupied chip area, assuming a vertical device geometry. Our data on lateral devices show that radial Esaki diodes deliver almost 7 times higher peak current, Jpeak = 2310 kA/cm2, than the maximum peak current of axial GaSb/InAs(Sb) Esaki diodes per unit chip area. The radial TFETs also deliver high peak current densities Jpeak = 1210 kA/cm2 while their axial counterparts at most carry Jpeak = 77 kA/cm2, normalized to the largest cross-sectional area of the nanowire.
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