Fundamental Research Division
The DRF at the CEA assemble approximately 6,000 scientists since January 2016.
Scientific result | Photonics
Nanotubes generally emit little or no light as their surface defects favor non-radiative recombinations (without photon emission). Scientists from INAC bypassed this difficulty by developing a new family of nanotubes with walls resembling a "layer cake" structure based on "quantum wells" that are 60 nanometers thick. Commonly used in light emitting diodes and semiconductor laser diodes, quantum wells are known for their remarkable optical properties due to electron confinement.
To produce such nanotubes, the physicists first made GaN nanowires on a sapphire substrate. Using the same equipment, they "coated" the nanowires with a radial heterostructure with GaN/InAlN quantum wells, deposited by metal–organic vapor-phase epitaxy. This was followed by in situ selective etching using H2/NH3 annealing. Under these conditions, only the GaN nanowires at the center are attacked, leading to the formation of quantum well nanotubes. Structural and optical analyzes show that the latter are not degraded by annealing.
The nanotubes obtained achieve excellent light emission efficiency in the UV range (330 nm) up to room temperature. This result paves the way for the production of new optical devices with nanotubes, ranging from UV sources to chemical or biological sensors.
This work was carried out in close collaboration with EPFL (École Polytechnique Fédérale de Lausanne, Switzerland). The project was granted support from the Franco-Swiss program "Hubert Curien and Germaine de Staël Partnerships" and Labex LANEF.
CEA is a French government-funded technological research organisation in four main areas: low-carbon energies, defense and security, information technologies and health technologies. A prominent player in the European Research Area, it is involved in setting up collaborative projects with many partners around the world.