[Paper Review] Photogalvanic Effect in Plasmonic Non-Centrosymmetric Nanoparticles

Sergei V. Zhukovsky, Viktoriia E. Babicheva+4 more|arXiv (Cornell University)|Dec 9, 2013

Photonic Crystals and Applications3 references3 citations

TL;DR

This paper proposes the plasmonic bulk photovoltaic (or photogalvanic) effect in non-centrosymmetric plasmonic nanoparticles, where asymmetrically shaped metallic nanoparticles in a semiconductor matrix generate directional photocurrents under uniform illumination due to shape-induced asymmetry. The effect enables directional photoelectron emission and offers a new mechanism for photodetection and photovoltaic applications.

ABSTRACT

Photoelectric properties of metamaterials containing asymmetrically shaped, similarly oriented metallic nanoparticles embedded in a homogeneous semiconductor matrix are theoretically studied. Due to the asymmetric shape of the nanoparticle boundary, photoelectron emission acquires a preferred direction, resulting in a photocurrent flow in that direction when nanoparticles are uniformly illuminated by a homogeneous plane wave. This effect is the direct analogy of the photogalvanic effect known to exist in media with certain asymmetries in their crystal structure, such as lithium niobate or quartz. Termed the plasmonic bulk photovoltaic (or photogalvanic) effect, the reported phenomenon is valuable for characterizing photoemission and photoconductive properties of plasmonic nanostructures, and can find many uses for photodetection and photovoltaic applications.

Motivation & Objective

• To investigate photoelectric properties in metamaterials with asymmetrically shaped metallic nanoparticles embedded in a semiconductor matrix.
• To explore how structural asymmetry in nanoparticle shape induces directional photocurrents under uniform illumination.
• To establish a plasmonic analog of the bulk photovoltaic effect observed in non-centrosymmetric crystals like quartz or lithium niobate.
• To demonstrate the potential of such nanostructures for enhancing photoconductive and photoemission responses in optoelectronic devices.

Proposed method

• Theoretical modeling of photoelectron emission from plasmonic nanoparticles with broken inversion symmetry.
• Use of a homogeneous plane wave to uniformly illuminate the nanoparticle array in a semiconductor matrix.
• Analysis of photocurrent generation based on the asymmetric shape of the nanoparticle boundary.
• Application of principles analogous to the bulk photovoltaic effect in non-centrosymmetric crystals to plasmonic systems.
• Modeling of electron emission dynamics under illumination, focusing on directionality due to geometric asymmetry.
• Evaluation of the system's response using electromagnetic and transport theory in non-centrosymmetric nanostructures.

Experimental results

Research questions

• RQ1 Can asymmetrically shaped plasmonic nanoparticles generate directional photocurrents under uniform illumination?
• RQ2 How does the shape-induced asymmetry in nanoparticle boundaries lead to net photocurrent flow?
• RQ3 To what extent does the plasmonic bulk photovoltaic effect resemble the classical photogalvanic effect in crystals?
• RQ4 What are the implications of this effect for designing efficient photodetectors and photovoltaic devices?
• RQ5 How does the photocurrent direction correlate with the geometric asymmetry of the nanoparticle structure?

Key findings

• The plasmonic bulk photovoltaic effect enables directional photocurrent generation in non-centrosymmetric metallic nanoparticles under uniform illumination.
• The effect arises from shape-induced asymmetry in the nanoparticle boundary, which breaks inversion symmetry and directs photoelectron emission.
• The phenomenon is analogous to the photogalvanic effect in non-centrosymmetric crystals such as lithium niobate and quartz.
• The mechanism provides a new pathway for engineering directional photoresponse in plasmonic nanostructures.
• The effect is robust under homogeneous plane wave illumination, indicating potential for practical photodetection and photovoltaic applications.
• The study establishes a theoretical foundation for characterizing photoemission and photoconductive behavior in asymmetric plasmonic systems.