Photon emitters, detectors and converters
Research areas:
- Microwave photonics
- Nanowire carrier diffusion induced light emitting diodes.
- Making and characterisation of semiconductor micro-LED using cathodoluminescence
Microwave photonics
Microwave photons are one of the main interaction media in solid-state quantum devices such as superconducting and semiconducting qubits. We study experimentally and theoretically microwave photons interacting with electrons in semiconductor nanostructures in the so-called circuit quantum electrodynamics (cQED) setup. For the electronic part of the system, we focus on using quantum dots that enable to build photodetectors and emitters in the microwave domain and strong coherent coupling between electric charge and microwave photons in the electrical circuits.
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Key publications:
- S. Haldar et al, Energetics of Microwaves Probed by Double Quantum Dot Absorption. Phys. Rev. Lett. 130, 087003
- W. Khan et al. Efficient and continuous microwave photoconversion in hybrid cavity-semiconductor nanowire double quantum dot diodes. Nature Communications. 12, 1, 5130.
Nanowire carrier diffusion-induced light emitting diodes.
Here we are working towards a nanowire light emitting diode architecture where the active parts do not have to be directly sandwiched in between electrical contacts but carrier diffusion from a higher band gap material into a lower band gap nanowire material can lead to highly polarized, directional and efficient luminescence. This is inspired by the work on carrier diffusion-induced luminescence in thin films done at Aalto University in Finland.
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Making and characterisation of semiconductor micro-LED using cathodoluminescence
We grow pyramids of InGaN, which are converted to platelets, with following growth of quantum wells on the top, to make micro LEDs. All three basic colours: red, green and blue are now achievable. The morphology and the defects are investigated with the help of cathodoluminescence, which provides necessary spatial resolution to investigate these sub-micron structures.
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Key publications:
A. Gustafsson, et al, From InGaN pyramids to micro-LEDs characterized by cathodoluminescence, Nano Express 2 (1) 014006 (2021)
M. Khalilian, et al, Coherently strained and dislocation-free architectured AlGaN/GaN submicron-sized structures, Nano Select 3 471–484 (2022)