New Paper on the Efficient light extraction in subwavelength GaAs/AlGaAs nanopillars for nanoscale light-emitting devices

This work reports on high extraction efficiency in subwavelength GaAs/AlGaAs semiconductor nanopillars. We achieve up to 37-fold enhancement of the photoluminescence (PL) intensity from sub-micrometer (sub-µm) pillars without requiring back reflectors, high-Qdielectric cavities, nor large 2D arrays or plasmonic effects.

This is a result of a large extraction efficiency for nanopillars <500 nm width, estimated in the range of 33-57%, which is much larger than the typical low efficiency (∼2%) of micrometer pillars limited by total internal reflection. Time-resolved PL measurements allow us to estimate the nonradiative surface recombination of fabricated pillars.

We conclusively show that vertical-emitting nanopillar-based LEDs, in the best-case scenario of both reduced surface recombination and efficient light out-coupling, have the potential to achieve notable large external quantum efficiency (∼45%), whereas the efficiency of large µm-pillar planar LEDs, without further methods, saturates at ∼2%. These results offer a versatile method of light management in nanostructures with prospects to improve the performance of optoelectronic devices including nanoscale LEDs, nanolasers, single-photon sources, photodetectors, and solar cells.

The full article can be found here.

Bruno Romeira*, Jérôme Borme, Hélder Fonseca, João Gaspar, and Jana B. Nieder*, Optics Express, Vol. 28, Issue 22, pp. 32302-32315 (2020) 

Meet Ekaterina Malysheva, ChipAI PhD Researcher at the Eindhoven University of Technology, The Netherlands

What inspired you to pursue a career in science?
Curiosity has always been the main driving force in my life - "why" was most likely the main question of my life, and it still remains. In childhood, I learned that humanity does not know all the answers to "why" questions, but there are some people for whom the search for answers has become a profession. That inspires me in the same way as people are inspired by space or deep ocean explorers.

How did you get where you are in your career path?
I come from Novosibirsk, which is the largest city in Siberia. This place is known not only for its cold weather but also for its big scientific centre. There I received a bachelor's degree in semiconductor physics and moved to Moscow to continue my studies in a master's degree in photonics. There I discovered the area of integrated photonics and began to search for the opportunity to continue research in this direction. Out of all other options, ChipAI project’s idea really surprised me by its novelty, and I realized that I want to be a part of this team.

How would you explain the importance of your research to the ChipAI project to a non-scientific person?
Many people have heard about neural networks and how its application in our every-day life - from target advertising and chatbots on the internet to self-driving cars. However, computing systems that we are currently using are not very energy-efficient and fast in calculating large scale neural networks, which limits their scope. At the same time, the most energy-efficient neural system known to humans is the brain, and the fastest thing in the universe is light. The goal of ChipAI project is to combine these two concepts and create a human brain-inspired light-driven computing system for very efficient neural network calculation.

What inspires you about science?
Science does not ask you to believe in anything - just look with your own eyes. And no matter how long people are trying to understand nature, there will always be room for more research.

How do you see the future of your Research?
Photonics has the potential to become a new generation of electronics - making complex calculations faster and more accessible. But there are lots of unknown in this area - how to make devices on-chip very small and efficient, how to integrate components together, which architecture will provide the best performance. I think the future of my research is more in technology development and scalability of current structures and systems-on-chip.

Briefly, what is a ‘day in your life’?
I’m trying to wake up at 7 am every day to have some time for sport or a short walk in the morning. At 8-9 I’m starting to work - either at home or taking a bike ride to the laboratory. I like to work more in the laboratory - despite the fact it’s more unpredictable, you can always see physical results with your own eyes. During the day it’s always nice to have a break and talk with a colleague, even if it’s online. At 6 pm I’m finishing with work and starting evening activities - it can be archery, online dance classes or just cooking.

In the context of ChipAI please describe your experience in being involved in a European project.
Being part of a European project is a very fascinating experience - many researchers with different backgrounds and capabilities come together to work on a common goal. This opens up opportunities for a better understanding of the general problem, exchange of experience and keeping motivated while working altogether.

18-Month Meeting Update | ChipAI Project

On September 24th the partners of the H2020 ChipAI project met online for the 18-month meeting update of the activities of the project related to neuromorphic nanophotonic circuits and chips for neural-inspired optical interconnections and computing. The project is funded by the Horizon2020 program from the European Commission on the call H2020-EU.1.2.1. - FET Open.

ChipAI project includes collaborations between research institutes, universities and companies representing different business sectors. The consortium in the project consists of project partners-participants, where Research and Development (R&D), Small and Medium Enterprises (SME)and Industry are represented.

ChipAI aims at developing nanoscale photonic chips capable to deliver compact, high-bandwidth and energy-efficient CPU’s using optically interconnected spiking neuron-like sources and detectors.

Kick-Off Meeting | ChipAI Project

On March 13-14 the partners of the H2020 ChipAI project met in Braga for the kick-off meeting. The project is funded by the Horizon2020 program from the European Commission on the call H2020-EU.1.2.1. - FET Open.

CHIPAI project includes collaborations between research institutes, universities and companies representing different business sectors. The consortium in the project consists of project partners participants, where Research and Development (R&D), Small and Medium Enterprises (SME)and Industry are represented.

ChipAI aims at developing nanoscale photonic chips capable to deliver compact, high-bandwidth and energy efficient CPU’s using optically interconnected spiking neuron-like sources and detectors.