POB seminar - Pierre Lottigier - "InGaN/GaN quantum wells on Si(111) substrate: Nonradiative recombination channels & Light emission efficiency improvement"


Event details

Date 06.06.2023
Hour 18:1519:15
Speaker Pierre Lottigier
Category Conferences - Seminars
Event Language English
EPFL Photonics Chapter (EPC) is pleased to invite you to our monthly POB (Pizza-Optics-Beer) seminar! It is set to take place on Tuesday, June 6, 2023, at 18:15 in CO 122. This POB seminar will be concluded by the awards ceremony of our photo contest.

For organizational purposes, please register for the event using this doodle before June 6, 2023.
This month, Pierre Lottigier will give a talk on his work "InGaN/GaN quantum wells on Si(111) substrate: Nonradiative recombination channels & Light emission efficiency improvement" :
To improve our LED lighting technologies, it is of prime importance to understand what impacts light-emission efficiency. The formation of threading dislocations during heteroepitaxial growth of semiconductors has historically been considered as a major source of nonradiative recombination in the active region of III-nitride based optoelectronic devices.
To question this, we investigated the efficiency of typical active layers consisting of single InGaN/GaN quantum wells (QWs) grown on thin (< 1 μm) GaN buffer layers on silicon (111) substrates exhibiting very high threading dislocation densities.
In this talk, I will first present intriguing results from various mesoscopic photoluminescence measurements. Despite the high defect density, we show that the QW emission efficiency significantly increases upon the insertion of an In-containing underlayer, whose role is to prevent the introduction of point defects during the growth of InGaN QWs.
Hence, we demonstrate that point defects play a key role in limiting the InGaN QW efficiency, even in samples where their density (∼ 3 × 109 cm−2) is much lower than that of threading dislocations (∼ 2 × 1010 cm−2). To explain the underlying nanoscale mechanisms of our questioning observations, our journey will take us through in-depth investigation of the recombination channels by means of cathodoluminescence mappings.


You don't know POBs?
POBs (Pizza-Optics-Beer) are monthly seminars organized by the student association EPFL Photonics Chapter.
A PhD or a postdoc gives a 20-minutes presentation about his/her research in photonics. Discussions continue informally around pizza and beers!
The event is free and open to anyone.

We thank the Doctoral Program in Photonics (EPDO), the Society of Photo-Optical Instrumentation Engineers (SPIE.), Optica and SwissPhotonics for their support.

Practical information

  • General public
  • Free
  • This event is internal


  • EPFL Photonics Chapter (EPC)


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