Materials Science is at the heart of new technological developments. These last years, the III-Nitride Team from the Materials Department's has mastered the growth InGaN/GaN NWs, with InGaN insertions characterized by high homogeneity, indium contents of up to 50% (well above the 20% achieved in two-dimensional materials) and abrupt interfaces. These axial heterostructures are particularly relevant for photonic, electronics and nano-energy applications. This know-how is now exploited through national and international collaborations.
In collaboration with Professor Y-H Cho's team from KAIST (South Korea), the C2N has grown GaN nanowires containing a set of three InGaN quantum disks behaving like quantum dots (QDs). These semiconductor-based structures play an essential role in solid-state quantum light sources because of their potential for room-temperature operation. However, undesired background emission from the surroundings deteriorates single-photon purity. Moreover, spectral diffusion causes inhomogeneous broadening and limits the applications of QDs in quantum photonic technologies. To overcome these obstacles, it is demonstrated that directly pumping carriers to the excited state of the QD reduces the number of carriers generated in the vicinities. The polarization-controlled quasi-resonant excitation is applied to InGaN QDs embedded in GaN nanowire. By employing this method, the Prof. Cho’s team has demonstrated reduced linewidth from 353 to 272 μeV, and an improvement of the second-order correlation value from 0.470 to 0.231. Therefore, a greater single-photon purity can be obtained at higher temperatures.
These results illustrated the back cover of Small.
References
Enhancement of Single-Photon Purity and Coherence of III-Nitride Quantum Dot with Polarization-Controlled
Quasi-Resonant Excitation
Seongmoon Jun1, Minho Choi1, Baul Kim1, Martina Morassi2, Maria Tchernycheva2, Hyun Gyu Song1, Hwan-Seop Yeo1, Noëlle Gogneau2, Yong-Hoon Cho1
Small 2023, 19, 2205229
DOI : https://doi.org/10.1002/smll.202205229
1 Department of Physics and KI for the NanoCentury, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon, 34141 Republic of Korea
2 Center for Nanosciences and Nanotechnologies, Paris-Saclay University, CNRS, UMR9001, Boulevard Thomas Gobert, Palaiseau, 91120 France
Contact C2N : Noëlle Gogneau
Keywords : Linewidth, InGaN/GaN Nanowires, Polarization, Quantum Dots, Quantum Emitters, Quasi-Resonant Excitation, Single-photon Purity
Figure : The InGaN quantum dot embedded in the GaN nanowire is excited by the quasi-resonant excitation laser: after relaxation of each electron and hole, a single photon is emitted by the recombination of the ground state electron and hole.
