Conference Presentation: CMD 2022

Two of the group gave oral presentations at CMD29 in Manchester.

Group PhD student Hoyeon Choi reported his work on the “Impact of Microstructure of Crystallinity driven singlet fission efficiency in diF-TES-ADT“, a collaboration between Jenny Clark (Sheffield) our our group.

Group PDRA Stephen Church reported his work on “Disentangling gain, distributed losses and end-facet losses in freestanding nanowires lasers using automated high-throughput micro-spectroscopy“, a collaboration between Huiyun Liu (UCL) and our group.

New Paper: Optical Characterisation of Nanowire Lasers

Uses of nanowire lasers

Group postdoc Stephen Church and PhD student Ruqaiya Al-Abri collaborated with Dhruv Saxena at Imperial College London to produce a review of methods to characterise nanowire lasers. This article, forming part of a celebration issue for the birthday of colleague Prof. Chennupati Jagadish (at the Australian National University) seeks to address many of the challenges in characterising nanowire lasers that may challenge new researchers to the field.

Reference: Optical characterisation of nanowire lasers, Stephen A. Church, Ruqaiya Al-Abri, Patrick Parkinson and Dhruv Saxena, Prog. Quant. Elec. (2022) DOI: 10.1016/j.pquantelec.2022.100408

Panel discussion

Patrick took part in a virtual panel discussion featuring collaborator Prof. Fu Lan (Australian National University) on the topic of nanowire quantum well arrays.

The ICANX talk was moderated by Haixia Zhang of Peking University, and featured Weida Hu (SITP) and Noushin Nasir (Macquarie).

The session is available to view at https://www.ican-x.com/talks.

Funded PhD position with A*STAR

The group is now advertising for a funded PhD position as part of the A*STAR ARAP scheme, in collaboration with Kedar Hippalgaonkar of A*STAR and NTU in Singapore. The project will build on the high-throughput techniques developed in the Manchester group, and the Bayesian optimization approaches at A*STAR, to apply Bayesian driven yield optimization to optoelectronic nanowires.

More details about the project are available at the FindAPhD site. The closing date is April 1st.

New Paper: Defect-Free Axially Stacked GaAs/GaAsP Nanowire Quantum Dots with Strong Carrier Confinement

Transmission electron microscopy and room-temperature photoluminescence of a dot-in-wire structure.

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

New Publication: Self-Catalyzed AlGaAs Nanowires and AlGaAs/GaAs Nanowire-Quantum Dots on Si Substrates

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

New Paper : Facet-Related Non-uniform Photoluminescence in Passivated GaAs Nanowires

(Left) SEM image of a single 250nm diameter GaAs nanowire with {112} facets highlighted and (Right) recombination measured in the {110} region (blue) and {112} region (red), showing emission quenching at these surfaces.

Our collaborative work on spatially inhomogeneous recombination in semiconductor nanowires has been published in a special issue of Frontiers in Chemistry. The work, led by Dr. Nian (Jenny) Jiang at the University of Cambridge reports the spatially varying emission intensity from passivated nanowires. By comparing the bulk emission to buried quantum well emission, we show that the a reduction in emission is related to {112}-faceted surfaces at the base of the wires.

This work solves a long-standing question in optoelectronic nanowires – why does the emission vary for nominally uniform structures? It provides two routes to avoiding this variation, through quantum well emission and by tuning the surface reconstruction to favour {110} side-walls.

Reference: Facet-Related Non-uniform Photoluminescence in Passivated GaAs Nanowires, Nian Jiang, Hannah Joyce, Patrick Parkinson, Jennifer Wong-Leung , Hark Hoe Tan and Chennupati Jagadish, Frontiers in Chemistry, 8, 1136 (2020), DOI: 10.3389/fchem.2020.607481

New Paper: Carrier dynamics and recombination mechanisms in InP twinning superlattice nanowires

(a) Twinning superlattice nanowire on substrate, (b) high-resolution SEM and (c) TEM image showing superlattice.

A new paper has been published in Optics Express, led by collaborator Xiaoming Yuan at Central South University (Changsha) and growth colleagues in the group of Prof. Jagadish at Australian National University.

In this work, novel “twinning-superlattice” nanowires are grown. Once passivated, this growth method produces extremely high quality nanowires, with carrier lifetimes of over 7ns. This work made use of the Manchester iTCSPC spectrometer, built by group PhD student Stefan Skalsky to study the low fluence dynamics at room temperture.

This growth method opens up a new facet in crystal-phase engineering for nanowire optoelectronics.

Reference: Carrier dynamics and recombination mechanisms in InP twinning superlattice nanowires, Xiaoming Yuan, Kunwu Liu, Stefan Skalsky, Patrick Parkinson, Long Fang, Jun He, Hark Hoe Tan, and Chennupati Jagadish, Optics Express 28, 16795 (2020) DOI: 10.1364/OE.388518