New Grant – EPSRC Impact Accelerator with Kubos Semi

The group has been awarded a 1-year “impact accelerator” grant with Kubos Semi, to fund a 6 month secondment of group PDRA Stephen Church. In this project, Stephen will translate our high-throughput methodology towards in-line optimization of emerging semiconductor materials.

Kubos develop cubic-phase GaN which can be grown on large diameter silicon carbide-on-silicon substrates for scale up of high-efficiency LEDs, and emission across the spectrum.

The project runs from October 2022-September 2023.

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

New Paper: Holistic Determination of Optoelectronic Properties using High-Throughput Spectroscopy of Surface-Guided CsPbBr3 Nanowires

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.

Open data

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

Nanowire Week 2022: Talks and Posters

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Nanowire week 2022

Group members Dr Stephen Church and Nikesh Patel have presented their work at the 2022 Nanowire Week meeting in Chamonix, France.

Stephen gave an oral presentation on his recent research on “Nanowire facet reflectivity and lasing performance using high-throughput interferometry“.

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Nikesh presented a poster on his work on “High Intra- and Interwire Uniformity in 2D Radial GaAsP/GaAs Core/Shell Triple Quantum Well Structures

MRS Fall 2021 – Mobility, Quantum Efficiency and Defect Density from High Throughput Spectroscopy of CsPbBr3 Nanowires

Stephen Church will present a talk on his recent work on holistic modelling using high-throughput spectroscopy virtually at MRS Fall 2021. This work, in collaboration with Prof Ernesto Joselevich at the Weizmann Institute uses high-throughput multimodal techniques to simultaneously model mobility, quantum efficiency and defect density from a single correlative study.