Group PDRA Stephen Church presented his work on nanolaser characterization at APC22 in Maastricht. He described our high-throughput methodology to understand the relative contributions of gain, end facet and cavity for photonic integrated application.
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
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 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“.
Nikesh presented a poster on his work on “High Intra- and Interwire Uniformity in 2D Radial GaAsP/GaAs Core/Shell Triple Quantum Well Structures“
The group will again offer an 8-week paid summer internship to work on developing a cloud-based solution for high-throughput data management. This position is only available to current University of Manchester students in their penultimate year of study.
The role will sit alongside PhD and postdoctoral staff in the group, to work on an existing basic method to store and query experimental data produced in the lab. It requires a familiarity with experimental data, the concept of metadata, and python programming.
Further details and the application form can be found at https://careerconnect.manchester.ac.uk/leap/jobSearch.html?id=25265&service=Careers+Service
Details about the scheme are available at https://www.manchester.ac.uk/study/undergraduate/teaching-learning/methods-materials/research/.
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.
Patrick gave a remote invited talk in the Low Dimensional Materials and Devices session of SPIE 2021, hybrid hosted in San Diego.
He spoke about “High-throughput spectroscopy of semiconductor nanowires in the presence of inhomogeneity“ including new material from group members.
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
The group will be joined for the next 8 weeks by a summer intern through the “Learning Through Research” program at Manchester. Andras will work on big-data methods for handling, sharing and processing large spectral and imaging datasets produced in the group.
Patrick gave an invited talk at a virtual Compound Semiconductor Week 2021 (nominally in Stockholm) on “A needle in a needlestack – exploiting functional inhomogeneity as a tool for optimized nanooptoelectronics“. This opened the B2 session “Nanowire growth and characterization“.