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.
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
Patrick gave a talk at ICPS Sydney, entitled “Hot-carrier dynamics in Zn-doped GaAs nanowires at sub-picosecond timescales via high-throughput spectroscopy“. This work, in collaboration with Martin Magnusson and colleagues at Lund University was led by group PhD student Ruqaiya Al-Abri.
Optoelectronic materials form the building blocks of crucial components of modern technology, including solar cells, CCDs, lasers and LEDs. The past decade has seen significant developments in materials science that enable the shrinking of these materials to the nano-scale. These advancements have also created entirely new technologies based around light manipulation. We can now create nano-scale light sources, nano-scale light detectors and nano-scale optics: so we can build a chip that performs processes using light instead of electrical signals.
An important component of these devices are nanowires: these can act as on-chip light sources and tiny optical fibers, essentially the power and wiring of a light based circuit. As materials are shrunk towards the nano-scale, their performance is affected strongly by their size, providing a handle to tune performance of these nanowires to suit the application. However, herein lies one of the major challenges of this technology; it remains difficult to accurately and repeatedly control the size of these nano-materials when they are made leading to an unwanted spread in their performance.
High-throughput experiments to study inhomogeneity
Stephen Church of the OMS Lab worked with colleagues in the Joselevich group at the Weizmann Institute in Israel to developed a methodology to optimize these nano-materials by harnessing the inherent variation using big data approaches. He has developed an automated microscope that can study the properties of more than 10,000 individual nano-wires with a suite of different optical experiments. This approach produces a vast dataset that, when considered together, describes the nano-material and can therefore be used to establish the best way to optimize their performance. Crucially, this approach requires very little prior knowledge of the sample and can be applied generally to new nano-materials.
Soft nanowires and the impact of strain
In their recent paper, we demonstrate this approach on wires made of halide perovskites, an emerging material touted for its superior light emission and detection. The material is also “soft”, deforming to fit on its substrate; this causes further spread in properties as the thickness of the wire changes. The big data approach shows the impact of this deformation on the color and the efficiency of light emission from the nano-wires, and shows how the degree of deformation varies across the population.
This publication is made up of more than just a journal report. The raw data has been made available via FigShare, and the analysis code via github. It is possible to explore and manipulate the raw data using the Google Colab platform.
Reference: Holistic Determination of Optoelectronic Properties using High-Throughput Spectroscopy of Surface-Guided CsPbBr3 Nanowires, Stephen A. Church, Hoyeon Choi, Nawal Al-Amairi, Ruqaiya Al-Abri, Ella Sanders, Eitan Oksenberg, Ernesto Joselevich and Patrick W. Parkinson, ACS Nano (2022) DOI: 10.1021/acsnano.2c01086
Group PhD students Ruqaiya Al-Abri and Hoyeon Choi have written an invited review article for JPhys Photonics, published today.
Lead author Ruqaiya Al-Abri describes this work:
Among the one-dimensional structures, semiconductor nanowires have attracted great attention; from the growth process to the production of functional devices they have been widely studied. The growth condition of the nanowires can lead to non-uniformity (disorder) in the crystal structure, morphology, and geometry of the nanowire. Consequently, this affects the functionality of individual and/or ensembles of nanowires. However, researchers have benefited from disorder; it has been shown that disorder can enhance the performance of ensemble of nanowires such as in photovoltaic devices. This review article attempts to understand the disorder in these structures, investigates the origin of the inhomogeneity within “interwire” and between “intrawire” nanowires, and outlines different approaches to correlate disorder to functional parameters and hence optimize the performance of the nanowires.
Reference: Measuring, controlling and exploiting heterogeneity in optoelectronic nanowires, Ruqaiya Al-Abri, Hoyeon Choi and Patrick Parkinson, JPhys Photonics, (2021) DOI:10.1088/2515-7647/abe282
The group welcomes Ruqaiya and Nawal as two new PhD students working in the group.
Ruqaiya will be working on nanolasers for on-chip photonics using both nanowires and nanoshapes developed by collaborators in UCL, ANU and China.
Nawal will be working on ultrafast photodetectors based on 2D materials with collaborators in Manchester and China.