Context :
Group-III nitride semiconductors (GaN, AlN, InN) are renowned for their outstanding light emission properties. For more than two decades, they have powered the blue and white LEDs used worldwide, thanks to highly efficient InGaN quantum wells (external quantum efficiency > 80%). In contrast, UV LEDs based on AlGaN quantum wells are still very inefficient (< 10%) and only recently became commercially available. Overcoming this limitation is a key challenge in optoelectronics: achieving efficient deep-UV emission (220–280 nm) would enable high-performance bactericidal applications such as water purification, surface sterilization, and virus inactivation.

Recently, two breakthrough concepts are promising to explore for UV-LEDs:
1. Deep-UV emission from GaN monolayers in AlN: Grow a few atomic monolayers (MLs) of GaN embedded in an AlN matrix. This extreme quantum confinement leads to deep-UV emission down to 220 nm. High emission efficiency is expected due to strong exciton binding, stable even at room temperature
2. Enhanced doping using graded digital GaN/AlN alloys: Use graded digital alloys (GaN)?/(AlN)? where n and m are the number of atomic layers. This architecture enables efficient n- and especially p-type doping, which is a major bottleneck in AlGaN. GaN is much easier to dope than AlN, making this approach very promising for device fabrication.

Scientific Targets :
The aim is to master monolayer growth using MOVPE (metal-organic vapor phase epitaxy), the most industrially relevant technique :
- M2 project: develop the growth of GaN monolayers on AlN substrates, study their deep-UV emission properties, and optimize growth conditions for self-limited single-layer deposition.
- PhD continuation: design and fabricate doped digital GaN/AlN alloys to build the first efficient deep-UV LEDs based on this architecture.

Lab background and collaboration:
The group has long-standing expertise in visible and UV light emission from nitride nanowires. We have already demonstrated 280 nm emission from (GaN)?/(AlGaN)? digital alloys, proving the viability of this approach. The project will be highly experimental (epitaxy, advanced structural and optical characterization) and conducted in close collaboration with Institut Néel for cathodoluminescence analysis and device processing.

Why join this project ?
Gain expertise in epitaxy, semiconductor physics, and optoelectronics. Work in a dynamic, collaborative environment with strong ties to industry. Contribute to the development of the next generation of deep-UV LEDs.