LPN research teams (photonics and nanostructures laboratory, Marcoussis) study the electrical and optical properties of the nano-objects they design and manufacture.
These nano-objects are made of various semiconductor materials and must be manufactured in clean rooms because the slightest dust particles could disrupt the operation of the devices obtained.
The first manufacturing step is lithography and, in the case of LPN, often electronic lithography because of its high resolution. Electron beams draw the patterns of objects in an electron-sensitive resin. After development, the resin will allow a template to be obtained by metal deposition. The last step will be engraving the patterns through the mask holes.
Very thin layer deposition techniques are molecular beam epitaxy and organometallic vapour phase epitaxy.
One structure often used is called a quantum dot. It consists of micro-pillars of semiconductor layers. First a stack of layers is made by successive epitaxies, then circular nickel studs are obtained at the top of this stack by lithography. These studs will be used as a template for reactive ion etching. They protect against engraving and cylindrical pillars are obtained under the studs.
Electrically or optically energized quantum dots release photons. At the LPN, they make it possible to create sources of entangled photon pairs.