Group postdoc Stephen Church presented a talk entitled “Disentangling Gain, Distributed Losses and End-Facet Losses in Freestanding Nanowire Lasers using Automated High-Throughput Micro-Spectroscopy” at UK Semiconductors in Sheffield, UK. This collaborative work between Manchester and colleagues in Zhejiang and University College London reported a multimodal correlative approach to studying nanolasers.
In a new collaboration between Yunyan Zhang and Profs. Huiyun Liu (UCL), Ana Sanchez (Warwick) and David Mowbray (Sheffield) we report the fabrication and measurement of a GaAs/GaAsP quantum dot-in-wire structure in Nano Letters.
While many material architechtures have been explored for single photon emission, the GaAsP-GaAs system provides strong carrier confinement and sharp interfaces, and can be grown directly onto a silicon substrate. This is a new route to silicon integrated single photon devices.
Reference: Defect-Free Axially Stacked GaAs/GaAsP Nanowire Quantum Dots with Strong Carrier Confinement, Yunyan Zhang, Anton V. Velichko, H. Aruni Fonseka, Patrick Parkinson, James A. Gott, George Davis, Martin Aagesen, Ana M. Sanchez, David Mowbray, and Huiyun Liu, Nano Lett. (2021), DOI: 10.1021/acs.nanolett.1c01461
A new collaborative paper led by Giorgos Boros and the team of Xuezhe Yu and Huiyun Liu at University College London has been published in J Phys Chem C. In this work, Giorgos reported the development of high quality ternary nanowires (AlGaAs) grown via MBE. While the AlGaAs/GaAs heterostructure system is well known in planar films, it has proven challenging to explore in the nanowire architecture.
Reference: Self-Catalyzed AlGaAs Nanowires and AlGaAs/GaAs Nanowire-Quantum Dots on Si Substrates, Giorgos Boros et al., J Phys Chem C. 2021, DOI: 10.1021/acs.jpcc.1c03680
Group PhD student Stefan Skalsky’s paper on semiconductor nanowire lasing has just been published in Light: Science and Applications. In this new work, Stefan used his newly developed Interferometric Time-Correlated Single Photon Counting system (i-TCSPC) to measure the coherence length of laser emission from nanowires grown by the Liu group at UCL. These measurements allowed the direct calculation of the nanowire mirror reflectivity.
During this study, Stefan found that it was possible to use indirect bandgap materials as a holding state for carriers before they relax into the emissive wells; this finding both allows multi-nanosecond lasing after a sub-picosecond excitation, and record low lasing thresholds through resonant excitation.
This work was supported by TEM provided by the Sanchez group at Warwick.
Reference: Heterostructure and Q-factor engineering for low-threshold and persistent nanowire lasing, Skalsky et al., Light: Science and Applications, 9, 43 (2020) https://doi.org/10.1038/s41377-020-0279-y
We have uploaded a new paper on quantum-dot-in-nanowire structures to the arXiv. Working with colleagues at University College London, the University of Warwick, the University of Sheffield and the University of Copenhagen, this work demonstrates the growth of high-quality GaAs quantum dot inclusions in a GaAsP nanowire, with evidence for single photon emission at low temperatures and emission to room temperature.
Reference: Defect-Free Axial GaAs/GaAsP Nanowire Quantum Dots with Strong Carrier Confinement, Zhang et al., arXiv:2002.07071