| 11. |
- Bao, Jiming, et al.
(författare)
-
Nanowire-induced Wurtzite InAs Thin Film on Zinc-Blende InAs Substrate
- 2009
-
Ingår i: Advanced Materials. - : Wiley. - 1521-4095 .- 0935-9648. ; 21:36, s. 3654-3654
-
Tidskriftsartikel (refereegranskat)abstract
- InAs pyramids and platelets on a zinc-blende InAs substrate are found to exhibit a wurtzite crystal structure. induced by wurtzite InAs nanowires, wurtzite InAs thin film and its associated zinc-blende/wurtzite heterocrystalline heterostructures may open up new opportunities in band-gap engineering and related device applications.
|
|
| 12. |
- Bao, Jiming, et al.
(författare)
-
Optical properties of rotationally twinned InP nanowire heterostructures
- 2008
-
Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 8:3, s. 836-841
-
Tidskriftsartikel (refereegranskat)abstract
- We have developed a technique so that both transmission electron microscopy and microphotoluminescence can be performed on the same semiconductor nanowire over a large range of optical power, thus allowing us to directly correlate structural and optical properties of rotationally twinned zinc blende InP nanowires. We have constructed the energy band diagram of the resulting multiquantum well heterostructure and have performed detailed quantum mechanical calculations of the electron and hole wave functions. The excitation power dependent blue-shift of the photoluminescence can be explained in terms of the predicted staggered band alignment of the rotationally twinned zinc blende/wurzite InP heterostructure and of the concomitant diagonal transitions between localized electron and hole states responsible for radiative recombination. The ability of rotational twinning to introduce a heterostructure in a chemically homogeneous nanowire material and alter in a major way its optical properties opens new possibilities for band-structure engineering.
|
|
| 13. |
- Barrigon, Enrique, et al.
(författare)
-
Nanoprobe-Enabled Electron Beam Induced Current Measurements on III-V Nanowire-Based Solar Cells
- 2019
-
Ingår i: 2019 IEEE 46th Photovoltaic Specialists Conference, PVSC 2019. - 0160-8371. - 9781728104942 ; , s. 2730-2733
-
Konferensbidrag (refereegranskat)abstract
- Electron beam induced current (EBIC) is a well-established tool to, among others, locate and analyze p-n junctions, Schottky contacts or heterostructures in planar devices and is now becoming essential to study and optimize devices at the nanoscale, like III-V nanowire (NW) based solar cells. Here, we report on EBIC measurements on III-V single NW solar cells as well as on fully processed NW devices. This paper also highlights the importance of EBIC to optimize short circuit current density values of fully processed nanowire solar cells of 1 mm2.
|
|
| 14. |
- Barrigón, Enrique, et al.
(författare)
-
Synthesis and Applications of III-V Nanowires
- 2019
-
Ingår i: Chemical Reviews. - : American Chemical Society (ACS). - 0009-2665 .- 1520-6890. ; 119:15, s. 9170-9220
-
Forskningsöversikt (refereegranskat)abstract
- Low-dimensional semiconductor materials structures, where nanowires are needle-like one-dimensional examples, have developed into one of the most intensely studied fields of science and technology. The subarea described in this review is compound semiconductor nanowires, with the materials covered limited to III-V materials (like GaAs, InAs, GaP, InP,...) and III-nitride materials (GaN, InGaN, AlGaN,...). We review the way in which several innovative synthesis methods constitute the basis for the realization of highly controlled nanowires, and we combine this perspective with one of how the different families of nanowires can contribute to applications. One reason for the very intense research in this field is motivated by what they can offer to main-stream semiconductors, by which ultrahigh performing electronic (e.g., transistors) and photonic (e.g., photovoltaics, photodetectors or LEDs) technologies can be merged with silicon and CMOS. Other important aspects, also covered in the review, deals with synthesis methods that can lead to dramatic reduction of cost of fabrication and opportunities for up-scaling to mass production methods.
|
|
| 15. |
- Berg, Alexander, et al.
(författare)
-
Growth and characterization of wurtzite GaP nanowires with control over axial and radial growth by use of HCl in-situ etching
- 2014
-
Ingår i: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248. ; 386, s. 47-51
-
Tidskriftsartikel (refereegranskat)abstract
- We report on the synthesis of non-tapered wurtzite (WZ) GaP nanowires by use of in-situ etching and the structural and optical characterization thereof. HCl was evaluated as an in-situ etchant in order to impede the onset of radial growth since the WZ crystal phase in GaP nanowires preferentially grows at relatively high growth temperatures around 600 degrees C, at which strong radial growth typically occurs. Transmission electron microscopy measurements confirmed non-tapered WZ GaP nanowires after growth. Photoluminescence characterization revealed defect related red emission, possibly related to transitions within the bandgap. Raman measurements show that the phonon energies in WZ GaP are very close in energy to the phonon energies in zinc blende GaP. (C) 2013 Elsevier B.V. All rights reserved.
|
|
| 16. |
|
|
| 17. |
- Berg, Alexander, et al.
(författare)
-
Radial Nanowire Light-Emitting Diodes in the (AlxGa1-x)yIn1-yP Material System
- 2016
-
Ingår i: Nano letters (Print). - Washington, DC : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 16:1, s. 656-662
-
Tidskriftsartikel (refereegranskat)abstract
- Nanowires have the potential to play an important role for next-generation light-emitting diodes. In this work, we present a growth scheme for radial nanowire quantum-well structures in the AlGaInP material system using a GaInP nanowire core as a template for radial growth with GaInP as the active layer for emission and AlGaInP as charge carrier barriers. The different layers were analyzed by X-ray diffraction to ensure lattice-matched radial structures. Furthermore, we evaluated the material composition and heterojunction interface sharpness by scanning transmission electron microscopy energy dispersive X-ray spectroscopy. The electro-optical properties were investigated by injection luminescence measurements. The presented results can be a valuable track toward radial nanowire light-emitting diodes in the AlGaInP material system in the red/orange/yellow color spectrum. © 2015 American Chemical Society.
|
|
| 18. |
- Bi, Zhaoxia, et al.
(författare)
-
Bottom-up approaches to microLEDs emitting red, green and blue light based on GaN nanowires and relaxed InGaN platelets
- 2023
-
Ingår i: Chinese Physics B. - : IOP Publishing. - 1674-1056. ; 32
-
Tidskriftsartikel (refereegranskat)abstract
- Miniaturization of light-emitting diodes (LEDs) with sizes down to a few micrometers has become a hot topic in both academia and industry due to their attractive applications on self-emissive displays for high-definition televisions, augmented/mixed realities and head-up displays, and also on optogenetics, high-speed light communication, etc. The conventional top-down technology uses dry etching to define the LED size, leading to damage to the LED side walls. Since sizes of microLEDs approach the carrier diffusion length, the damaged side walls play an important role, reducing microLED performance significantly from that of large area LEDs. In this paper, we review our efforts on realization of microLEDs by direct bottom-up growth, based on selective area metal–organic vapor phase epitaxy. The individual LEDs based on either GaN nanowires or InGaN platelets are smaller than 1 μm in our approach. Such nano-LEDs can be used as building blocks in arrays to assemble microLEDs with different sizes, avoiding the side wall damage by dry etching encountered for the top-down approach. The technology of InGaN platelets is especially interesting since InGaN quantum wells emitting red, green and blue light can be grown on such platelets with a low-level of strain by changing the indium content in the InGaN platelets. This technology is therefore very attractive for highly efficient microLEDs of three primary colors for displays.
|
|
| 19. |
- Bi, Zhaoxia, et al.
(författare)
-
From nanoLEDs to the realization of RGB-emitting microLEDs
- 2021
-
Ingår i: Semiconductors and Semimetals : Micro LEDs - Micro LEDs. - : Elsevier. - 0080-8784. ; 106, s. 223-251
-
Bokkapitel (refereegranskat)abstract
- MicroLED technology is expected to be the technology of choice for next-generation displays. Its advantages in various applications are reviewed. The challenges of microLED manufacturing, including red microLED realization, adequate efficiency, mass transfer, and structure and process design from a system perspective, are discussed with a special emphasis on how nano-scale material science may open new avenues toward solutions to key issues. Technical solutions to the main challenges are discussed in detail, including epitaxial growth of GaN nanowires, relaxed InGaN templates and InGaN planar red LEDs, as well as mass transfer technologies. Two primary approaches are described, one with extreme down-scaling of well-developed planar LED technology, the other where an emphasis is on the realization of nanoLEDs, on submicrometer scale, used as building blocks for all pixel sizes.
|
|
| 20. |
- Bi, Zhaoxia, et al.
(författare)
-
High In-content InGaN nano-pyramids : Tuning crystal homogeneity by optimized nucleation of GaN seeds
- 2018
-
Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 123:2
-
Tidskriftsartikel (refereegranskat)abstract
- Uniform arrays of submicron hexagonal InGaN pyramids with high morphological and material homogeneity, reaching an indium composition of 20%, are presented in this work. The pyramids were grown by selective area metal-organic vapor phase epitaxy and nucleated from small openings in a SiN mask. The growth selectivity was accurately controlled with diffusion lengths of the gallium and indium species, more than 1 μm on the SiN surface. High material homogeneity of the pyramids was achieved by inserting a precisely formed GaN pyramidal seed prior to InGaN growth, leading to the growth of well-shaped InGaN pyramids delimited by six equivalent 10 1 ̄ 1 facets. Further analysis reveals a variation in the indium composition to be mediated by competing InGaN growth on two types of crystal planes, 10 1 ̄ 1 and (0001). Typically, the InGaN growth on 10 1 ̄ 1 planes is much slower than on the (0001) plane. The formation of the (0001) plane and the growth of InGaN on it were found to be dependent on the morphology of the GaN seeds. We propose growth of InGaN pyramids seeded by 10 1 ̄ 1-faceted GaN pyramids as a mean to avoid InGaN material grown on the otherwise formed (0001) plane, leading to a significant reduction of variations in the indium composition in the InGaN pyramids. The InGaN pyramids in this work can be used as a high-quality template for optoelectronic devices having indium-rich active layers, with a potential of reaching green, yellow, and red emissions for LEDs.
|
|
