Publications de Wei Liu | EPFL Graph Search

Thermal management for gas lubricated, high-speed turbomachinery

Jürg Alexander Schiffmann, Luis Eric Olmedo Ocampo, Wei Liu, Wanhui Liu

High-speed turbomachinery is commonly designed to achieve high power densities. Limited space for active cooling results in a challenging thermal management. A thermal modeling approach leveraging modern declarative programming capabilities is presented, y ...

2023

Imaging Nonradiative Point Defects Buried in Quantum Wells Using Cathodoluminescence

Nicolas Grandjean, Jean-François Carlin, Raphaël Butté, Duncan Thomas Lindsay Alexander, Wei Liu, Wei Liu, Thomas Fjord Kjaersgaard Weatherley

Crystallographic point defects (PDs) can dramatically decrease the efficiency of optoelectronic semiconductor devices, many of which are based on quantum well (QW) heterostructures. However, spatially resolving individual nonradiative PDs buried in such QW ...

AMER CHEMICAL SOC2021

Impact of defects on Auger recombination in c-plane InGaN/GaN single quantum well in the efficiency droop regime

Nicolas Grandjean, Jean-François Carlin, Raphaël Butté, Yixing Chen, Gwénolé Jean Jacopin, Wei Liu, Camille Haller, Thomas Fjord Kjaersgaard Weatherley

We study the impact of non-radiative defects on Auger recombination in c-plane InGaN/GaN single quantum wells (SQWs) in the efficiency droop regime using high injection time-resolved photoluminescence. The defect density in the SQW is controlled by tuning ...

AMER INST PHYSICS2020

Ultrafast carrier dynamics in III-nitride nanostructures and LED quantum efficiency

Wei Liu, Wei Liu

Since the seminal report about the first Candela- class-brightness InGaN blue light- emitting diodes (LEDs) by Shuji Nakamura et al. in 1994, III-nitride semiconductors have been one of the most important platforms for optoelectronic devices. The achieve ...

EPFL2019

Impact of alloy disorder on Auger recombination in single InGaN/GaN core-shell microrods

Benoît Marie Joseph Deveaud, Gwénolé Jean Jacopin, Wei Liu, Georg Rossbach, Christian Mounir

We study the influence of local inhomogeneities on carrier recombination dynamics in single InGaN/GaN core-shell microrods (MRs) by means of time-resolved microphotoluminescence (TRPL) at 10 K. At low carrier density (similar to 10(11) cm(-2)), the carrier ...

2019

GaN surface as the source of non-radiative defects in InGaN/GaN quantum wells

Nicolas Grandjean, Jean-François Carlin, Raphaël Butté, Denis Martin, Gwénolé Jean Jacopin, Camille Haller, Wei Liu

Blue light-emitting diodes based on III-nitride semiconductors are nowadays widely used for solid-state lighting. They exhibit impressive figures of merit like an internal quantum efficiency close to 100%. This value is intriguing when considering the high ...

2018

Spatially dependent carrier dynamics in single InGaN/GaN core-shell microrod by time-resolved cathodoluminescence

Benoît Marie Joseph Deveaud, Gwénolé Jean Jacopin, Wei Liu, Georg Rossbach

AIP American Institute of Physics2018

Enhancement of Auger recombination induced by carrier localization in InGaN/GaN quantum wells

Nicolas Grandjean, Benoît Marie Joseph Deveaud, Raphaël Butté, Gwénolé Jean Jacopin, Wei Liu, Georg Rossbach, Lise Lahourcade, Mehran Shahmohammadi

The origin of efficiency droop in state-of-the-art quality In GaN/GaN and GaN/AlGaN quantum wells (QWs) grown on various crystal planes is studied by means of time-resolved photoluminescence spectroscopy associated with a precise determination of the QW ca ...

Amer Physical Soc2017

Exciton dynamics at a single dislocation in GaN probed by picosecond time-resolved cathodoluminescence

Nicolas Grandjean, Jean-François Carlin, Benoît Marie Joseph Deveaud, Gwénolé Jean Jacopin, Wei Liu

We investigate the dynamics of donor bound excitons (D degrees X-A) at T = 10K around an isolated single edge dislocation in homoepitaxial GaN, using a picosecond time-resolved cathodoluminescence (TR-CL) setup with high temporal and spatial resolutions. A ...

Amer Inst Physics2016

Carrier-density-dependent recombination dynamics of excitons and electron-hole plasma in m-plane InGaN/GaN quantum wells

Nicolas Grandjean, Benoît Marie Joseph Deveaud, Raphaël Butté, Gwénolé Jean Jacopin, Wei Liu

We study the carrier-density-dependent recombination dynamics in m-plane InGaN/GaN multiple quantum wells in the presence of n-type background doping by time-resolved photoluminescence. Based on Fermi's golden rule and Saha's equation, we decompose the rad ...

Amer Physical Soc2016