Theoretical predictions for hot-carrier generation from surface plasmon decay

Abstract

Decay of surface plasmons to hot carriers finds a wide variety of applications in energy conversion, photocatalysis and photodetection. However, a detailed theoretical description of plasmonic hot-carrier generation in real materials has remained incomplete. Here we report predictions for the prompt distributions of excited ‘hot’ electrons and holes generated by plasmon decay, before inelastic relaxation, using a quantized plasmon model with detailed electronic structure. We find that carrier energy distributions are sensitive to the electronic band structure of the metal: gold and copper produce holes hotter than electrons by 1–2 eV, while silver and aluminium distribute energies more equitably between electrons and holes. Momentum-direction distributions for hot carriers are anisotropic, dominated by the plasmon polarization for aluminium and by the crystal orientation for noble metals. We show that in thin metallic films intraband transitions can alter the carrier distributions, producing hotter electrons in gold, but interband transitions remain dominant.

Harvesting the loss: surface plasmon-based hot electron photodetection

“…Hot carriers are primarily generated with momentum parallel to the external field [31], which is generally parallel with the semiconductor interface in the case of an antenna, resulting in poor injection. Moreover, hot electron generation is also dependent on the plasmonic material employed [32,72,[76][77][78]. Several groups have explored the effects of the electronic structure of the metal on the generated carrier distributions [32,76] ( Figure 1F), and it has been shown that, in the interband transition regime, the electronic band structure of the metal plays an important role in determining both the energy and the momentum distribution of the generated hot carriers [32].…”

“…Hot electron transfer efficiencies can further be boosted by embedding the plasmonic nanostructures within the semiconductor, providing more momentum space for hot electron emission [86] (Figure 7A). In addition, it has been shown that the preferred carrier type for extraction, either electrons or holes, is dependent on the plasmonic material employed [32,72].…”

“…Several groups have explored the effects of the electronic structure of the metal on the generated carrier distributions [32,76] ( Figure 1F), and it has been shown that, in the interband transition regime, the electronic band structure of the metal plays an important role in determining both the energy and the momentum distribution of the generated hot carriers [32]. In fact, in this regime, none of the commonly used plasmonic materials, including gold, silver, aluminum, and copper, exhibit the isotropic momentum distribution assumed in Fowler's theory [32]. Additionally, the effects of phonons and surfaces on hot carriers have also been studied [79].…”

Strong exciton-localized plasmon coupling in a-Ge24Se76/AuNP heterostructure

“…There exists a pathway of photoinduced charge transfer from the semiconductor to the metal, which can be used to controllably vary the driving forces at the interface that leads to tunable optoelectronic properties. In this letter, we report the observation of a dramatic suppression of plasmonic as well as excitonic absorption in a-Ge 24 Exciton-plasmon coupling in a semiconductor/metallic hybrid structure can generate promising opportunities for new optical functionalities that are feasible with neither of the individual components of coupled states. 1,2 Although the coupling between the two quasi-particles, viz., plasmons and excitons are not yet fully understood, it is accepted that the surface plasmons in metal nanoparticles can trap and guide light at the nanoscale over broad spectral ranges.…”

“…15,16 As a result, we have an outstanding problem connecting the optical nonlinearity of excitons, which defines their photosensitivity, with the field enhancement shown by the plasmons. In this letter, we demonstrate plasmon-exciton interaction at the ultrafast time scale in an amorphous Ge 24 Se 76 /gold nanoparticle (AuNP) heterostructure, which can be controlled by varying the plasmon wavelength. Our studies show that the coupling in these heterostructures is strong enough such that the exciton and plasmon absorptions are dramatically quenched.…”