| 1. |
- Aberg, I, et al.
(författare)
-
Nanoscale tungsten aerosol particles embedded in GaAs
- 2002
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 80:16, s. 2976-2978
-
Tidskriftsartikel (refereegranskat)abstract
- GaAs containing buried nanoscale tungsten particles has been characterized electrically. The particles were produced using a special aerosol process and were embedded in GaAs by epitaxial overgrowth. Two different particle sizes were investigated separately. When the particle concentration was increased, a conductance drop of about 500 times was observed. A simulation model, based on a random distribution of the particles, was developed and used to support our findings. The major advantage of our method is the simplicity and low processing cost.
|
|
| 2. |
- Junno, Tobias, et al.
(författare)
-
Single-electron devices via controlled assembly of designed nanoparticles
- 1999
-
Ingår i: Microelectronic Engineering. - 0167-9317. ; 47:1-4, s. 179-183
-
Tidskriftsartikel (refereegranskat)abstract
- Single-electron transistors (SET) rely for their functionality on extreme control of lithography and lateral positioning as well as of properties of the building blocks from which the devices are built. By an aerosol-based nanoparticle fabrication we can prepare nanocrystals down to sub-10nm dimensions with metallic or semiconducting character, as well as having a core + shell design for definition of tunnel-gaps. We present here results for a type of device that is based on the possibility to design functionality in the internal structure of the nanoparticles which are used as building blocks. We use such pre-fabricated building blocks to construct coulomb blockade devices and show that they operate at temperatures above 150K.
|
|
| 3. |
- Lee, S. -K, et al.
(författare)
-
Reduction of the barrier height and enhancement of tunneling current of titanium contacts using embedded Au nano-particles on 4H and 6H silicon carbide
- 2002
-
Ingår i: Materials Science Forum. - : Trans Tech Publications Inc.. - 0255-5476 .- 1662-9752. ; 389-393:2, s. 937-940
-
Tidskriftsartikel (refereegranskat)abstract
- We have investigated the electrical characteristics of Ti Schottky contacts with embedded Au nano-particles on various types of epilayers of SiC (4H- and 6H-SiC). From our current-voltage (I-V) and capacitance-voltage (C-V) measurements, we observed that Ti Schottky contacts with embedded Au nano-particles had 0.19 eV (n-4H-SiC) and 0.15 eV (n-6H-SiC) lower barrier height than those of particle free Ti Schottky contacts. In order to understand this reduction of the Schottky barrier height (SBH) for Ti Schottky contacts with embedded Au nano-particles, it has been proposed that SBH lowering is caused by an enhanced electric field due to the small size of the Au nano-particles and the large SBH difference. We have also tested these contacts on highly doped n-and p-type SiC material to study ohmic contacts using linear TLM measurements.
|
|
| 4. |
- Lee, S. K., et al.
(författare)
-
Reduction of the Schottky barrier height on silicon carbide using Au nano-particles
- 2002
-
Ingår i: Solid-State Electronics. - 0038-1101 .- 1879-2405. ; 46:9, s. 1433-1440
-
Tidskriftsartikel (refereegranskat)abstract
- By the incorporation of size-selected Au nano-particles in Ti Schottky contacts on silicon carbide, we could observe considerably lower the barrier height of the contacts. This result could be obtained for both n- and p-type Schottky contacts using current-voltage and capacitance voltage measurements. For n-type Schottky contacts, we observed reductions of 0.19-0.25 eV on 4H-SiC and 0.15-0.17 eV on 6H-SiC as compared with particle-free Ti Schottky contacts. For p-type SiC, the reduction was a little lower with 0.02-0.05 eV on 4H- and 0.10-0.13 eV on 6H-SiC. The reduction of the Schottky barrier height is explained using a model with enhanced electric field at the interface due to the small size of the circular patch and the large difference of the barrier height between Ti and Au.
|
|
| 5. |
- Björk, Mikael, et al.
(författare)
-
One-dimensional heterostructures in semiconductor nanowhiskers
- 2002
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 80:6, s. 1058-1060
-
Tidskriftsartikel (refereegranskat)abstract
- We report on the growth of designed heterostructures placed within semiconductor nanowhiskers, exemplified by the InAs/InP material system. Based on transmission electron microscopy, we deduce the interfaces between InAs and InP to be atomically sharp. Electrical measurements of thermionic emission across an 80-nm-wide InP heterobarrier, positioned inside InAs whiskers 40 nm in diameter, yield a barrier height of 0.6 eV. On the basis of these results, we propose new branches of physics phenomena as well as new families of device structures that will now be possible to realize and explore.
|
|
| 6. |
- Björk, Mikael, et al.
(författare)
-
One-dimensional steeplechase for electrons realized
- 2002
-
Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 2:2, s. 87-89
-
Tidskriftsartikel (refereegranskat)abstract
- We report growth of one-dimensional semiconductor nanocrystals, nanowhiskers, in which segments of the whisker with different composition are formed, illustrated by InAs whiskers containing segments of InP. Our conditions for growth allow the formation of abrupt interfaces and heterostructure barriers of thickness from a few monolayers to 100s of nanometers, thus creating a one-dimensional landscape along which the electrons move. The crystalline perfection, the quality of the interfaces, and the variation in the lattice constant are demonstrated by high-resolution transmission electron microscopy, and the conduction band off-set of 0.6 eV is deduced from the current due to thermal excitation of electrons over an InP barrier.
|
|
| 7. |
- Borgström, Magnus, et al.
(författare)
-
Nanowires With Promise for Photovoltaics
- 2011
-
Ingår i: IEEE Journal of Selected Topics in Quantum Electronics. - 1077-260X. ; 17:4, s. 1050-1061
-
Tidskriftsartikel (refereegranskat)abstract
- Solar energy harvesting for electricity production is regarded as a fully credible future energy source: plentiful and without serious environmental concerns. The breakthrough for solar energy technology implementation has, however, been hampered by two issues: the conversion efficiency of light into electricity and the solar panel production cost. The use of III-V nanowires (NWs) in photovoltaics allows to respond to both these demands. They offer efficient light absorption and significant cost reduction. These low-dimensional structures can be grown epitaxially in dense NW arrays directly on silicon wafers, which are abundant and cheaper than the germanium substrates used for triple-junction solar cells today. For planar structures, lattice matching poses a strong restriction on growth. III-V NWs offer to create highly efficient multijunction devices, since multiple materials can be combined to match the solar spectrum without the need of tightly controlled lattice matching. At the same time, less material is required for NW-based solar cells than for planar-based architecture. This approach has potential to reach more than 50% in efficiency. Here, we describe our work on NW tandem solar cells, aiming toward two junctions absorbing different parts of the solar spectrum, connected in series via a tunnel diode.
|
|
| 8. |
- Borgström, Magnus T., et al.
(författare)
-
Towards Nanowire Tandem Junction Solar Cells on Silicon
- 2018
-
Ingår i: IEEE Journal of Photovoltaics. - 2156-3381. ; 8:3, s. 733-740
-
Tidskriftsartikel (refereegranskat)abstract
- The development of photovoltaics as a serious means of producing renewable energy has accelerated greatly in the last ten years, with prices for silicon-based solar cell systems dropping dramatically in the last few years. The next great opportunity for photovoltaics following this competitiveness in prices will be to enhance the cell and panel efficiencies. It is quite generally seen that the most viable platform on which this should be realized will be as augmented silicon solar cells, in which a top cell will be combined with the silicon bottom cell in a tandem configuration, by which the efficiency can be enhanced by a factor from 20% to 50%, depending on details of the approach. In this paper, we report on the status of one such approach, namely, with a top cell comprising III-V nanowires, connected to the bottom silicon cell in a two-terminal or four-terminal configuration. Among the most important opportunities, we show that a substrate-free growth, called Aerotaxy, offers a radical reduction in the total price picture. Besides the description of the key technical approaches, we also discuss the environmental issues.
|
|
| 9. |
- Deppert, Knut, et al.
(författare)
-
Aerosol fabrication of nanocrystals of InP
- 1999
-
Ingår i: Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers. - 0021-4922. ; 38:2 B, s. 1056-1059
-
Tidskriftsartikel (refereegranskat)abstract
- Nanocrystals of indium phosphide, with diameters of around 10nm, have been produced via an aerosol route. The method is based on the formation of monodisperse indium droplets and the subsequent reaction with phosphine at elevated temperature. The size of the final InP nanocrystal is self-limited by the size of the introduced size-selected In droplet. This size can be tuned carefully, thus this method allows a narrow size distribution of the nanocrystals. The kinetics of the reaction of In to produce InP depends on the temperature and the phosphine flow. Extensive high resolution transmission electron microscopy studies lead to a consistent picture of the process. Our approach opens the possibility for efficient production of size-selected semiconductor nanocrystals and it will allow new types of self-assembly and control of quantum dots.
|
|
| 10. |
- Deppert, Knut, et al.
(författare)
-
Aerotaxy: High throughput gas-phase epitaxy of nanostructures
- 2020
-
Konferensbidrag (refereegranskat)abstract
- Aerotaxy is an aerosol-based growth method for semiconductors and we present in detail how aerotaxy can be used to grow nanowires continuously with controlled nanoscale dimensions, with a high degree of crystallinity and remarkable throughput, including process details and our current understading of the growth processes. Catalytic size-selected Au aerosol particles travel through a heated flow-through reactor and mix with III–V precursor flux, which nucleates the growth of nanowires. We demonstrate that the method allows sensitive and reproducible control of the nanowire dimensions and shape. The reported continuous and potentially high-throughput method is expected to substantially reduce the cost of producing high-quality nanowires and may enable the low-cost fabrication of nanowire-based devices on an industrial scale.
|
|
