| 1. |
- Al-Abri, Ruqaiya, et al.
(författare)
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Sub-Picosecond Carrier Dynamics Explored using Automated High-Throughput Studies of Doping Inhomogeneity within a Bayesian Framework
- 2023
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Ingår i: Small. - 1613-6810. ; 19:33
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Tidskriftsartikel (refereegranskat)abstract
- Bottom–up production of semiconductor nanomaterials is often accompanied by inhomogeneity resulting in a spread in electronic properties which may be influenced by the nanoparticle geometry, crystal quality, stoichiometry, or doping. Using photoluminescence spectroscopy of a population of more than 11 000 individual zinc-doped gallium arsenide nanowires, inhomogeneity is revealed in, and correlation between doping and nanowire diameter by use of a Bayesian statistical approach. Recombination of hot-carriers is shown to be responsible for the photoluminescence lineshape; by exploiting lifetime variation across the population, hot-carrier dynamics is revealed at the sub-picosecond timescale showing interband electronic dynamics. High-throughput spectroscopy together with a Bayesian approach are shown to provide unique insight in an inhomogeneous nanomaterial population, and can reveal electronic dynamics otherwise requiring complex pump-probe experiments in highly non-equilibrium conditions.
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| 2. |
- Manchester, The Univ., et al.
(författare)
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High-throughput spectroscopy of semiconductor nanowires in the presence of inhomogeneity
- 2021
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Ingår i: - : SPIE. ; , s. 20-20
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Konferensbidrag (refereegranskat)abstract
- Controllable doping in semiconductor nanowires is essential for development of optoelectronic devices. Despite great progress, a fundamental challenge remains in controlling the uniformity of doping, particularly in the presence of relatively high levels of geometrical inhomogeneity in bottom-up growth. A relatively high doping level of 1E18 cm-3 corresponds to just ~1000 activated dopants in a 2µm long, 50nm diameter nanowire. High-throughput photoluminescence spectroscopy enables the collection of doping distributions across many (>10k) nanowires, but geometric variation adds additional uncertainty to the modelling. We present an approach that uses large datasets of doping and emission intensity to infer both doping and diameter across a growth, and apply Bayesian methods to study the underlying distributions in Zn-doped aerotaxy-grown GaAs nanowires. This new big-data enabled approach provides a route to exploit inherent inhomogeneity to reveal fundamental recombination mechanisms.
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| 3. |
- Zhang, Yunyan, et al.
(författare)
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Highly Strained III-V-V Coaxial Nanowire Quantum Wells with Strong Carrier Confinement
- 2019
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 13:5, s. 5931-5938
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Tidskriftsartikel (refereegranskat)abstract
- Coaxial quantum wells (QWs) are ideal candidates for nanowire (NW) lasers, providing strong carrier confinement and allowing close matching of the cavity mode and gain medium. We report a detailed structural and optical study and the observation of lasing for a mixed group-V GaAsP NW with GaAs QWs. This system offers a number of potential advantages in comparison to previously studied common group-V structures (e.g., AlGaAs/GaAs) including highly strained binary GaAs QWs, the absence of a lower band gap core region, and deep carrier potential wells. Despite the large lattice mismatch (∼1.7%), it is possible to grow defect-free GaAs coaxial QWs with high optical quality. The large band gap difference results in strong carrier confinement, and the ability to apply a high degree of compressive strain to the GaAs QWs is also expected to be beneficial for laser performance. For a non-fully optimized structure containing three QWs, we achieve low-temperature lasing with a low external (internal) threshold of 20 (0.9) μJ/cm2/pulse. In addition, a very narrow lasing line width of ∼0.15 nm is observed. These results extend the NW laser structure to coaxial III-V-V QWs, which are highly suitable as the platform for NW emitters.
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