The Role of Surface Roughness in Plasmonic-Assisted Internal Photoemission Schottky Photodetectors

Grajower, Meir; Levy, Uriel; Khurgin, Jacob B.

doi:10.1021/acsphotonics.8b00643

Cited by 57 publications

(56 citation statements)

References 50 publications

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“…[16,18,19] (as demonstrated in the current manuscript), existing theory of electron tunnelling (see e.g., Ref. [58]) and the vast knowledge accumulated on heterogeneous catalysis on the various chemical parameters that affect the reaction rate can now provide, for the first time, the necessary framework to analyze the relative efficiency of non-thermal and thermal effects and distinguish between optical and chemical aspects in these previously published papers, as well as in future papers on the topic. In this Supplementary Information Section, we compute the temperature of the catalyst pellet described in [29, paper III] and [30, paper IV], respectively.…”

Section: Discussionmentioning

confidence: 56%

Thermal effects – an alternative mechanism for plasmon-assisted photocatalysis

2020

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Recent experiments claimed that the enhancement of catalytic reaction rates occurs via the reduction of activation barriers driven by non-equilibrium ("hot") electrons in plasmonic metal nanoparticles. These experiments place plasmonic photo-catalysis as a promising path for enhancing the efficiency of various chemical reactions. Here, we argue that what appears to be photo-catalysis is in fact thermo-catalysis, driven by the well-known plasmon-enhanced ability of illuminated metallic nanoparticles to serve as heat sources. Specifically, we point to some of the most important papers in the field, and show that a simple theory of illumination-induced heating can explain the extracted experimental data to remarkable agreement, with minimal to no fit parameters. We further show that any small temperature difference between the photocatalysis experiment and a control experiment performed under uniform external heating is effectively amplified by the exponential sensitivity of the reaction, and very likely to be interpreted incorrectly as "hot" electron effects.

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Section: Discussionmentioning

confidence: 56%

Thermal effects – an alternative mechanism for plasmon-assisted photocatalysis

2020

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“…In order to test this (rather simple) estimate, we ran our calculation with an additional tunneling term of the form −γ T g(ε)f (ε), where γ T = 10 13 Hz and 10 15 Hz, corresponding to a slow (100 femtosecond) and fast (few femtosecond) tunneling time (which is extremely fast, as realistic tunneling times were shown to be as short as 100 fs only in the best case scenario, see e.g., [69]); g is centered at ≈ 1.5eV above the Fermi energy and has an energy width of a few hundreds of meV. In Fig.…”

Section: G Evaluating the Power Density For Different Processmentioning

confidence: 99%

“Hot” electrons in metallic nanostructures—non-thermal carriers or heating?

2019

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Understanding the interplay between illumination and the electron distribution in metallic nanostructures is a crucial step towards developing applications such as plasmonic photocatalysis for green fuels, nanoscale photodetection and more. Elucidating this interplay is challenging, as it requires taking into account all channels of energy flow in the electronic system. Here, we develop such a theory, which is based on a coupled Boltzmann-heat equations and requires only energy conservation and basic thermodynamics, where the electron distribution, and the electron and phonon (lattice) temperatures are determined uniquely. Applying this theory to realistic illuminated nanoparticle systems, we find that the electron and phonon temperatures are similar, thus justifying the (classical) single-temperature models. We show that while the fraction of high-energy “hot” carriers compared to thermalized carriers grows substantially with illumination intensity, it remains extremely small (on the order of 10−8). Importantly, most of the absorbed illumination power goes into heating rather than generating hot carriers, thus rendering plasmonic hot carrier generation extremely inefficient. Our formulation allows for the first time a unique quantitative comparison of theory and measurements of steady-state electron distributions in metallic nanostructures.

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“…Shown in Fig.13c but this approach entirely neglects the possibility of backscattering into the metal. Another approach [70] was to use the explicit interface roughness scattering explicitly to obtain the enhancement of extraction efficiency by a factor of a few. That model, however, could only be applied to a relatively small roughness, and, as matter of fact, neglected enhanced backscattering as well.…”

Section: A Transport Efficiencymentioning

confidence: 99%

Fundamental limits of hot carrier injection from metal in nanoplasmonics

Khurgin

2019

Nanophotonics

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155

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Evolution of the non-equilibrium carriers excited in the process of decay of surface plasmon polaritons (SPPs) in metal is described for each step -from the carrier generation to their extraction from the metal. The relative importance of various carrier generating mechanism is discussed. It is shown that both carrier generation and their decay are inherently quantum processes as for realistic illumination conditions no more than a single SPP per nanoparticle exists at a given time. As a result, the distribution of nonequilibrium carriers cannot be described by a single temperature. It is also shown that the originally excited carriers that have not undergone a single electron-electron scattering event, are practically the only ones that contribute to the injection. The role of the momentum conservation in the carrier extraction is discussed and it is shown that if all the momentum conservation rules are relaxed, it is the density of states in the semiconductor/dielectric that determines the ultimate injection efficiency. A set of recommendations aimed at improving the efficiency of plasmonic-assisted photodetection and (to a lesser degree) photocatalysis is made in the end.

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The Role of Surface Roughness in Plasmonic-Assisted Internal Photoemission Schottky Photodetectors

Cited by 57 publications

References 50 publications

Thermal effects – an alternative mechanism for plasmon-assisted photocatalysis

Thermal effects – an alternative mechanism for plasmon-assisted photocatalysis

“Hot” electrons in metallic nanostructures—non-thermal carriers or heating?

Fundamental limits of hot carrier injection from metal in nanoplasmonics

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