2020 Undergraduate Research Showcase


Using Distributed Bragg Reflectors to Improve Photon Collection From Quantum Dots

Document Type

Student Presentation

Presentation Date


Faculty Sponsor

Dr. Paul J. Simmonds


Quantum dots (QDs) are novel nanostructures that, when excited by electricity or light, emit photons useful for devices such as LEDs, quantum light sources, and solar cells. QDs emit light in all directions, with wavelengths characteristic of QD size and shape. We are interested in studying how these QDs emit light, but at times the light emission is too low in intensity to accurately detect with photoluminescence (PL) spectroscopy. To improve detection, we use molecular beam epitaxy (MBE) to insert a distributed Bragg reflector (DBR) into the sample structure, with the goal of reflecting additional photons into the PL detector. Theoretical modeling shows that changes in DBR thickness alter the reflected light wavelength, allowing us to tune the reflectivity of the DBR to match the emission spectra from GaAs QDs. Initial results show that we have accurately synthesized two DBR structures tuned to wavelengths of 1000 and 1100 nm. These results will be used to optimize the DBR structure and MBE growth conditions to provide maximum reflectivity. This work will give us a deeper understanding of our QDs, which is essential for device integration and continued QD research.

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