Host Institution : CEA
Laboratory : iNAC
Call to project : Starting (PE7)
Project name : TERAGAN – GaN Quantum Devices for T-Ray Sources
Amount : 1,63 M€
T-rays, often called terahertz radiation or sub-millimeter waves, are loosely defined as the wavelengths from 30 µm to 1,000 µm, or the frequencies from 10 THz to 300 GHz. This non-ionizing radiation appears as a harmless alternative to x-rays in medical, biological and security screening. Current solutions in terms of coherent sources of T-rays either require cryogenic temperatures or are relatively bulky equipments based on optically-pumped materials. The solid-state recourse consisting of GaAs-based quantum cascade lasers presents an intrinsic limitation in operation temperature: The low energy of the longitudinal-optical (LO) phonon in arsenide compounds hinders laser emission beyond 180 K at 4 THz, and forces operation below the liquid nitrogen temperature (< 70 K) for frequencies below 1 THz.
Overcoming this limitation requires a technology revolution through introduction of a new material system. This project aims at exploring a novel semiconductor technology for high-performance photonic devices operating in the T-ray spectral region. The advanced materials that we will investigate consist of nitride-based [GaN/Al(Ga,In)N] super-lattices and nano-wires, where we can profit from unique properties of III-nitride semiconductors, namely the large LO-phonon energy and the strong electron-phonon interaction. Our target is to adapt the quantum cascade design and fabrication technology to these new materials, characterized by intense internal polarization fields.
Our project aims at pushing inter-subband transitions in this material family to unprecendently long wavelengths, in other to cover the whole T-ray spectral gap with coherent solid-state sources operating at room temperature and above.