Modification of Carrier Dynamics in InGaN/GaN MQWs by Resonant and Non-resonant Metallic Nanoparticles

Meg Mahat Physics, University of North Texas, Denton, Texas, USA Antonio Llopis Physics, University of North Texas, Denton, Texas, USA Electrical Engineering, Duke University, Durham, North Carolina, USA Sergio Pereira CICECO, University of Aveiro, Aveiro, Portugal Ian Watson SUPA Institute of Photonics, University of Strathclyde, Glasgow, UK Arkadii Krokhin Physics, University of North Texas, Denton, Texas, USA Arup Neogi Physics, University of North Texas, Denton, Texas, USA IFFS, University of Engineering Science and Technology, Chengdu, China

In previous work we have demonstrated non-resonant enhancement of photoluminescence in InGaN/GaN multiple quantum wells (QWs) with metal nanoparticles embedded into naturally occurring inverted hexagonal pits (IHPs). [1] This enhancement is associated with a relatively longer effective photoluminescence lifetime. It arises due to electrostatic interaction between carriers within the QWs and image charges induced in the neutral metallic NPs within the QW.

In order to better understand the carrier dynamics of this effect and how it differs from resonant plasmonic interactions, we have performed ultrafast differential absorption measurements on samples infiltrated with both non-resonant Au NPs as well as Ag NPs whose plasmon resonance overlaps with the QWs. Using a pump-probe setup with significant path folding, we are able to observe the carrier dynamics due to intraband carrier scattering process in the ps range as well as the interband carrier relaxation process in the ns range.

The results we present here demonstrate that both resonant and non-resonant interaction with nanoparticles have significant effects on the behavior of carriers within the QWs.

arup@unt.edu

References

A. Llopis, et al., “Electrostatic mechanism of strong enhancement of light emitted by semiconductor quantum wells”, Phys. Rev. B 87, 239902 (2013).