| 1. |
- Borgström, Magnus, et al.
(författare)
-
In Situ Etching for Total Control Over Axial and Radial Nanowire Growth
- 2010
-
Ingår i: Nano Reseach. - : Springer Science and Business Media LLC. - 1998-0124 .- 1998-0000. ; 3:4, s. 264-270
-
Tidskriftsartikel (refereegranskat)abstract
- We report a method using in situ etching to decouple the axial from the radial nanowire growth pathway, independent of other growth parameters. Thereby a wide range of growth parameters can be explored to improve the nanowire properties without concern of tapering or excess structural defects formed during radial growth. We demonstrate the method using etching by HCl during InP nanowire growth. The improved crystal quality of etched nanowires is indicated by strongly enhanced photoluminescence as compared to reference nanowires obtained without etching.
|
|
| 2. |
|
|
| 3. |
- Wallentin, Jesper, et al.
(författare)
-
Changes in Contact Angle of Seed Particle Correlated with Increased Zincblende Formation in Doped InP Nanowires.
- 2010
-
Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 10:12, s. 4807-4812
-
Tidskriftsartikel (refereegranskat)abstract
- Nanowires grown with the vapor-liquid-solid method commonly exhibit polytypism, showing both zincblende and wurtzite crystal structure. We have grown p-type InP nanowires using DEZn as a dopant precursor and studied the wetting of the seed particle and the nanowire crystal structure. The nanowires grown with high DEZn molar fractions exhibit deformed seed particles after growth. We observe 20% smaller nanowire diameter at the highest DEZn molar fraction, indicating a significant increase in contact angle of the seed particle during growth. The decrease in diameter correlates with an increase in zincblende segment length as measured by TEM. We explain the results with a modified nucleation model.
|
|
| 4. |
- Wallentin, Jesper, et al.
(författare)
-
Degenerate p-doping of InP nanowires for large area tunnel diodes
- 2011
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 99:25
-
Tidskriftsartikel (refereegranskat)abstract
- We have investigated p-doping of InP nanowires using diethyl zinc. Two-terminal devices showed non-linear source-drain characteristics and p-type gate dependence. Electron beam induced current measurements were employed to determine minority carrier diffusion lengths. We used large-area tunnel diodes to demonstrate degenerate doping, showing peak current densities of up to 0.11 A/cm(2) and room temperature peak to valley current ratios of 5.3. These results demonstrate that high p- and n-doping, paired with sharp doping profiles, can be achieved in InP nanowires. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3669697]
|
|
| 5. |
- Wallentin, Jesper, et al.
(författare)
-
Electron Trapping in InP Nanowire FETs with Stacking Faults.
- 2012
-
Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 12:1, s. 151-155
-
Tidskriftsartikel (refereegranskat)abstract
- Semiconductor III-V nanowires are promising components of future electronic and optoelectronic devices, but they typically show a mixed wurtzite-zinc blende crystal structure. Here we show, theoretically and experimentally, that the crystal structure dominates the conductivity in such InP nanowires. Undoped devices show very low conductivities and mobilities. The zincblende segments are quantum wells orthogonal to the current path and our calculations indicate that an electron concentration of up to 4.6 × 10(18) cm(-3) can be trapped in these. The calculations also show that the room temperature conductivity is controlled by the longest zincblende segment, and that stochastic variations in this length lead to an order of magnitude variation in conductivity. The mobility shows an unexpected decrease for low doping levels, as well as an unusual temperature dependence that bear resemblance with polycrystalline semiconductors.
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
- Wallentin, Jesper, et al.
(författare)
-
Probing the Wurtzite Conduction Band Structure Using State Filling in Highly Doped InP Nanowires.
- 2011
-
Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 11:Online May 23, 2011, s. 2286-2290
-
Tidskriftsartikel (refereegranskat)abstract
- We have grown InP nanowires doped with hydrogen sulfide, which exhibit sulfur concentrations of up to 1.4%. The highest doped nanowires show a pure wurtzite crystal structure, in contrast to bulk InP which has the zinc blende structure. The nanowires display photoluminescence which is strongly blue shifted compared with the band gap, well into the visible range. We find evidence of a second conduction band minimum at the gamma point about 0.23 eV above the band edge, in excellent agreement with recent theoretical predictions. Electrical measurements show high conductivity and breakdown currents of 10(7) A/cm(2).
|
|
| 9. |
- Wallentin, Jesper, et al.
(författare)
-
Semiconductor-Oxide Heterostructured Nanowires Using Postgrowth Oxidation.
- 2013
-
Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 13:12, s. 5961-5966
-
Tidskriftsartikel (refereegranskat)abstract
- Semiconductor-oxide heterointerfaces have several electron volts high-charge carrier potential barriers, which may enable devices utilizing quantum confinement at room temperature. While a single heterointerface is easily formed by oxide deposition on a crystalline semiconductor, as in MOS transistors, the amorphous structure of most oxides inhibits epitaxy of a second semiconductor layer. Here, we overcome this limitation by separating epitaxy from oxidation, using postgrowth oxidation of AlP segments to create axial and core-shell semiconductor-oxide heterostructured nanowires. Complete epitaxial AlP-InP nanowire structures were first grown in an oxygen-free environment. Subsequent exposure to air converted the AlP segments into amorphous aluminum oxide segments, leaving isolated InP segments in an oxide matrix. InP quantum dots formed on the nanowire sidewalls exhibit room temperature photoluminescence with small line widths (down to 15 meV) and high intensity. This optical performance, together with the control of heterostructure segment length, diameter, and position, opens up for optoelectrical applications at room temperature.
|
|
| 10. |
- Wallentin, Jesper, et al.
(författare)
-
Single GaInP nanowire p-i-n junctions near the direct to indirect bandgap crossover point
- 2012
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 100:25
-
Tidskriftsartikel (refereegranskat)abstract
- Axially defined GaInP single nanowire (NW) p-i-n junctions are demonstrated, with photocurrent response and yellow-green electroluminescence near the indirect bandgap crossover point at 2.18 eV (569 nm). We use DEZn and H2S as p- and n-type dopants, and find that they both affect the material composition and the crystal structure. The photovoltaic efficiency is comparable to single NW devices from binary III-V materials. These results demonstrate the potential of GaInP nanowires as a high-bandgap material for multijunction solar cells and light-emitting devices in the visible regime. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4729929]
|
|
