Patra Saroj Kanta, Schulz Stefan
Tyndall National Institute, University College Cork , Cork T12 R5CP , Ireland.
Department of Electrical Engineering , University College Cork , Cork T12 YN60 , Ireland.
Nano Lett. 2020 Jan 8;20(1):234-241. doi: 10.1021/acs.nanolett.9b03740. Epub 2019 Dec 3.
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.
非经典光发射，如纠缠光子发射和单光子发射，因其在未来量子技术应用中的重要性而引起了广泛关注。在这项工作中，我们研究了纤锌矿型（In，Ga）N/GaN量子点用于新型非经典光发射（即双光子发射）的潜力。我们基于全原子多体框架进行的计算表明，由于量子点中随机合金涨落导致的载流子局域化、自旋轨道耦合效应、纤锌矿晶体结构以及内建电场的综合作用，产生了一种与迄今用于双光子发射的更为“传统”的闪锌矿型（In，Ga）As量子点截然不同的激子精细结构。我们在此展示并讨论了能量最低的四个激子态都是明亮的，并且发射线偏振光。此外，这些激子态中的三个基本简并。所有这些结果都与合金微观结构无关。而且，我们的计算揭示了较大的激子结合能（>35 meV），超过了室温下的热能。因此，（In，Ga）N/GaN量子点是实现高效双光子发射的非常有前景的候选材料，可能在高温以及宽发射波长范围内实现。
