Periodic Reporting for period 1 - ThunderLight (Electrically-driven next generation of plasmonic nanosource of light)
Période du rapport: 2021-06-01 au 2023-05-31
This project aims to achieve an electrically driven nanosource of light with improved emission performance (efficiency, coherence, photon statistics) compared to the state of the art. Such a nanosource consists of semiconductor nanocrystals (quantum dots which are a source of single photons) positioned precisely inside the nanogap of an optical gold nanoantenna. This device constitutes an extremely rich platform for the control of light and corresponds to an important step for the integration of light nanosources with nanoelectronics. The emission of light is activated by the local electrical excitation of the optical modes of the nanoantenna by inelastic electronic tunneling from the tip of a scanning tunneling microscope (STM). Thus, an in-depth optical and electro-optical characterization of the nanosource is necessary to understand and control all the elementary processes on which the performance of the device depends. Our project is carried out through the use of a clean room equipped with state-of-the-art equipment and a dedicated STM coupled with an optical microscope.
One of the main goals of the project is the electrical excitation of an emitter in a plasmonic nanocavity at room temperature. The project combines different elements: the realization of a nanometric device; coupling quantum emitters to a plasmon cavity / bowtie antenna to control the emission characteristics of a single photon source; and the electrical excitation of such a device.
The project ended earlier (7 months out of 24) due to the recruitment of the coordinator for a permanent researcher position at the CNRS. As a result, most of the work done consists in the production of gold antennas in a clean room and their optical characterization. This step is the first in the production of the nanodevice and has made it possible to highlight certain limits in the control of the spacing between the nanoantennas produced, a key step to ensure the repeatability and use of the device. Presentations open to the public during the Fête de la Science were held to discuss this project, showed images of nanoantennas, and how to excite them with a scanning tunneling microscope.
One of the main goals of the project is the electrical excitation of an emitter in a plasmonic nanocavity at room temperature. The project combines different elements: the realization of a nanometric device; coupling quantum emitters to a plasmon cavity / bowtie antenna to control the emission characteristics of a single photon source; and the electrical excitation of such a device.
The project ended earlier (7 months out of 24) due to the recruitment of the coordinator for a permanent researcher position at the CNRS. As a result, most of the work done consists in the production of gold antennas in a clean room and their optical characterization. This step is the first in the production of the nanodevice and has made it possible to highlight certain limits in the control of the spacing between the nanoantennas produced, a key step to ensure the repeatability and use of the device. Presentations open to the public during the Fête de la Science were held to discuss this project, showed images of nanoantennas, and how to excite them with a scanning tunneling microscope.
During the period concerned, after training on the different configurations, we fabricated several samples on different substrates (glass, gold, ITO) for several bowtie antennas (two sizes, two intervals, and four shapes) in a clean room. The sizes of the gaps have been varied with a 10nm control at this time and which should be refined during the process. We have also made antennas consisting of three or four triangular nanoparticles, in order to modify the optical response of the antenna and its ability to direct light. These results and more general information about the project were discussed through several public and scientific events: Fête de la Science, two summer schools in the field of photonics, and a one-day workshop on Charge Transfer.
Compared to the state of the art, we have achieved gap sizes of the order of ten nanometers on three different substrates (glass, ITO, and gold film). However, due to the short period of the project, the reproducibility of the process needs to be confirmed. We have also introduced other bowtie antenna geometries that would require further study and characterization to show their interest in controlling light emission.