Publications by Nicolas Grandjean

Quantifying carbon site switching dynamics in GaN by electron holography

Nicolas Grandjean, Jean-François Carlin, Raphaël Butté

Off-axis electron holography is utilized to identify point defect reactions and quantify their dynamics by probing the time and temperature dependence of the Fermi level upon annealing. The methodology is illustrated using implanted carbon (C) in GaN, wher ...

2025

Monolayer-Thick GaN/AlN Quantum Well Anodes and Far-UVC Field Emission Device at 226 nm

Nicolas Grandjean, Jean-François Carlin

Far-UVC light sources in the spectral range of200-230 nm effectively kill bacteria and deactivate viruses while being not harmful to health, enabling persistent disinfection of air and surfaces in the presence of humans. So far only excimer lamps have been ...

IEEE2025

Multi-octave bandwidth supercontinuum generation in crystalline Aluminum Nitride-on-sapphire waveguides

Nicolas Grandjean, Jean-François Carlin, Camille Sophie Brès, Raphaël Butté

Applications such as optical clocks, gas spectroscopy, and optical coherent tomography stand to benefit significantly from the integration of on-chip supercontinuum sources. Materials exhibiting both second- and third-order nonlinearities are particularly ...

International Society for Optical Engineering2025

On the influence of the buffer layer on the optical quality of AlN-on-sapphire epilayers for photonic integrated devices

Nicolas Grandjean, Jean-François Carlin, Camille Sophie Brès, Raphaël Butté

In the last decade, aluminum nitride (AlN) has proven to be an attractive material for both linear and nonlinear integrated photonics, due to its large transparency window, its low propagation losses and the presence of both second- and third-order nonline ...

SPIE2025

Defects in InGaN QW Structures: Microscopic Properties and Modeling

Nicolas Grandjean

Defects can significantly modify the electrical and optical properties of quantum well (QW) structures based on InGaN. We present an overview of our recent results on the properties of point and extended defects in InGaN/GaN QW devices. By analyzing single ...

SPIE2025

VN-VIn divacancies as the origin of non-radiative recombination centers in InGaN quantum wells

Nicolas Grandjean, Jean-François Carlin, Raphaël Butté, Yao Chen

In this paper, we investigate the nature of surface defects originating from the high-temperature (HT) GaN buffer and their incorporation into InGaN quantum wells (QWs) grown using the metalorganic vapor phase epitaxy technique. In particular, we conduct a ...

AIP Publishing2025

Two faces of superradiance in tandem-cavity ridge waveguide heterostructures

Nicolas Grandjean

Cooperative emission due to spontaneous build-up and rapid decay of macroscopic polarization in a strongly inverted gain medium is drastically different from the lasing dynamics. The medium polarization and not the cavity field drives the emission from a d ...

SPIE2024

Decoupling Interlayer Spacing and Cation Dipole on Exciton Binding Energy in Layered Halide Perovskites

Nicolas Grandjean, Rosario Scopelliti, Kevin Sivula, Jun Ho Yum, Han-Hee Cho, Simon Nussbaum, Yeonju Kim

Layered halide perovskites (LHPs) are emerging semiconductor materials due to their superior environmental stability compared to that of traditional halide perovskites. While LHPs have tunable optoelectronic properties, quantum and dielectric confinement e ...

2024

AlN-based anodes for far-UVC field emission device at 225 nm

Nicolas Grandjean, Jean-François Carlin

We report on progress in the realization of Field Emission Devices (FED) with AlN-based anodes emitting in the spectral window of 200-230nm for persistent disinfection of air and surfaces in the presence of humans. Modeling, experimental studies, and trade ...

SPIE2024

Identification and thermal healing of focused ion beam-induced defects in GaN using off-axis electron holography

Nicolas Grandjean, Jean-François Carlin, Raphaël Butté, Yi Wang

Thermal healing of focused ion beam-implanted defects in GaN is investigated by off-axis electron holography in TEM. The data reveal that healing starts at temperatures as low as about 250 degrees C. The healing processes result in an irreversible transiti ...

Iop Publishing Ltd2024