Publications de Raphaël Butté

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

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

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

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

Sub-20 kHz low-frequency noise near ultraviolet butt-coupled fiber Bragg grating external cavity laser diode

Nicolas Grandjean, Raphaël Butté

We present a butt-coupled InGaN fiber Bragg grating (FBG) semiconductor laser diode operating below 400 nm in the single-mode emission regime. This compact coherent laser source exhibits an intrinsic linewidth of 14 kHz in the near-UV range and a side-mode ...

AIP American Institute of Physics2024

Origin of giant enhancement of phase contrast in electron holography of modulation-doped n-type GaN

Nicolas Grandjean, Jean-François Carlin, Raphaël Butté

The electron optical phase contrast probed by electron holography at n-n+ GaN doping steps is found to exhibit a giant enhancement, in sharp contrast to the always smaller than expected phase contrast reported for p-n junctions. We unravel the physical ori ...

2024

Investigation of the Impact of Point Defects in InGaN/GaN Quantum Wells with High Dislocation Densities

Nicolas Grandjean, Jean-François Carlin, Raphaël Butté, Duncan Thomas Lindsay Alexander, Thomas Fjord Kjaersgaard Weatherley, Pierre Christophe Lottigier, Davide Maria Di Paola

In this work, we report on the efficiency of single InGaN/GaN quantum wells (QWs) grown on thin (

MDPI2023

Polariton lasing in AlGaN microring with GaN/AlGaN quantum wells

Nicolas Grandjean, Jean-François Carlin, Raphaël Butté

Microcavity polaritons are strongly interacting hybrid light-matter quasiparticles, which are promising for the development of novel light sources and active photonic devices. Here, we report polariton lasing in the UV spectral range in microring resonator ...

AIP Publishing2023

Optical and thermal characterization of a group-III nitride semiconductor membrane by microphotoluminescence spectroscopy and Raman thermometry

Nicolas Grandjean, Jean-François Carlin, Raphaël Butté, Ian Michael Rousseau

We present the simultaneous optical and thermal analysis of a freestanding photonic semiconductor membrane made from wurtzite III-nitride material. By linking microphotoluminescence spectroscopy with Raman thermometry and other spectroscopic techniques, we ...

Amer Physical Soc2023