Abstract
III–V semiconductors nanowires (NW) have recently attracted a significant interest for their potential application in the development of high efficiency, highly-integrated photonic devices and in particular for the possibility to integrate direct bandgap materials with silicon-based devices. Here we report the absorbance properties of GaAs-AlGaAs-GaAs core-shell-supershell NWs using photo-acoustic spectroscopy (PAS) measurements in the spectral range from 300 nm to 1100 nm wavelengths. The NWs were fabricated by self-catalyzed growth on Si substrates and their dimensions (length ~5 μm, diameter ~140–150 nm) allow for the coupling of the incident light to the guided modes in near-infrared (IR) part of the spectrum. This coupling results in resonant absorption peaks in the visible and near IR clearly evidenced by PAS. The analysis reveal broadening of the resonant absorption peaks arising from the NW size distribution and the interaction with other NWs. The results show that the PAS technique, directly providing scattering independent absorption spectra, is a very useful tool for the characterization and investigation of vertical NWs as well as for the design of NW ensembles for photonic applications, such as Si-integrated light sources, solar cells, and wavelength dependent photodetectors.
Highlights
The growing need for fast, integrated, nanoscale, low-cost photonic devices has triggered intensive developments of semiconductor nanowires (NWs)
In this work we used the photo-acoustic spectroscopy (PAS) technique to study absorbance properties of GaAs-AlGaAs heterostructure NWs grown by self-catalyzed technique on lithography-free Si/SiOx patterns[29]
The NWs were grown by molecular beam epitaxy on p-Si(111) wafers using lithography-free Si/SiOx patterns for defining the nucleation sites
Summary
The growing need for fast, integrated, nanoscale, low-cost photonic devices has triggered intensive developments of semiconductor nanowires (NWs). A single III-V semiconductor vertical NW has good waveguiding properties for energies above the bandgap owing to high refractive indices, and it can support a number of discrete photonic modes. These confined modes can lead to resonant absorption at specific wavelengths mainly defined by the combination of materials properties and their geometric dimensions[1]. In all work that follows we consider the light normally incident on the cross-section plane, where k is parallel to L
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