Exploring the Potential of c-Plane Indium Gallium Nitride Quantum Dots for Twin-Photon Emission

SK Patra and S Schulz, NANO LETTERS, 20, 234-241 (2020).

DOI: 10.1021/acs.nanolett.9b03740

Nonclassical light emission, such as entangled and single-photon emission, has attracted significant interest because of its importance in future quantum technology applications. In this work, we study the potential of wurtzite (In,Ga)N/GaN quantum dots for novel nonclassical light emission, namely, twin-photon emission. Our calculations, based on a fully atomistic many-body framework, reveal that the combination of carrier localization due to random alloy fluctuations in the dot, spin- orbit coupling effects, underlying wurtzite crystal structure, and built-in electric fields leads to an excitonic fine structure that is very different from that of more "conventional" zinc-blende (In,Ga)As dots, which have been used so far for twin photon emission. We show and discuss here that the four energetically lowest exciton states are all bright and emit linearly polarized light. Furthermore, three of these excitonic states are basically degenerate. All of these results are independent of the alloy microstructure. Also, our calculations reveal large exciton binding energies (>35 meV), which exceed the thermal energy at room temperature. Therefore, (In,Ga)N/GaN dots are very promising candidates for achieving efficient twin photon emission, potentially at high temperatures and over a wide emission wavelength range.

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