Plasmonic Hot-Carriers in Channel-Coupled Nanogap Structure for Metal–Semiconductor Barrier Modulation and Spectral-Selective Plasmonic Monitoring

Abstract

Plasmonic hot-carriers, which are induced by plasmons at metal surfaces, can be used to convert photon energy into excited carriers over a subwavelength region and provide a new means to realize photodetection within the subband-gap region of semiconductor materials. However, the barrier height of the metal−semiconductor junction affects the behavior of the plasmon-induced hot-carriers and limits the electrical response of photodetection. High electrical responsivity, achieved by manipulating the barrier height using plasmon-induced hot electrons, is desired to broaden the possible applications. Here we report a plasmonic channelcoupled nanogap structure, where the barrier height of the metal−semiconductor junction is altered upon the excitation of plasmon-induced hot-carriers. The structure consists of semiconductor channels and metal slabs forming nanogaps, which sustain coupled plasmons and confine light to the semiconductor−metal interfaces. In contrast to conventional Schottky barriers and ohmic contacts, in which plasmon-induced hot-carriers and the generation of electron−hole pairs by photoabsorption cause an increase in the photocurrent, the generation of plasmon-induced hot-carriers at the resonant wavelength results in an increase in the junction barrier height and a decrease in the photocurrent induced by photoabsorption. By modifying the barrier height, the plasmon resonance can be monitored from the electrical response with a high spectral resolution and a large modulation.

All-Si Photodetectors with a Resonant Cavity for Near-Infrared Polarimetric Detection

“…However, as shown in Fig. 1e, hot electrons generated through the internal photoemission effect (IPE) [10, 11, 15] by surface plasmons in the metallic layer can diffuse to the Si substrate and flow over the Schottky barrier as the extra photo-current, enabling the detection in NIR. Furthermore, in this scenario, the subwavelength Au grating on the nanowire top acts as a polarizer as well as a resonator tuning the detecting wavelengths, determined by the dimensions of the structure.…”

“…Being the major material of the semiconductor industry, silicon has emerged as optoelectronic devices in recent years due to their distinct optical and electrical properties [6–8], well-established process, and high compatibility with the developed CMOS technology [9]. Furthermore, recent achievements in silicon photonics [10, 11] offer a promising pathway to realize the novel form of PDs by integrating Si nanowire detectors [12, 13] with photonic structures for new application such as polarimetric detection.…”

Progress in the Utilization Efficiency Improvement of Hot Carriers in Plasmon-Mediated Heterostructure Photocatalysis

“…Based on this, near 2.4-fold improvements were realized in the photocatalytic hydrogen production by embedding Au multimers in MoS 2 , compared to pure MoS 2 (Figure 4g). cross section [66][67][68]. It has been reported that the amplitudes of such EM enhancements are mainly related to the space of the gap and numbers of plasmonic metallic units.…”

“…In such an integrating system, the EM fields are localized at the gap between the two or more units, and this globe field enhancement comes from coupling effects in the interaction of the modes of SPs, consequently resulting in a large absorption Another effective way for achieving enhanced EM fields is to design gap "hot spots" structures by arranging the numbers of metallic units rationally. In such an integrating system, the EM fields are localized at the gap between the two or more units, and this globe field enhancement comes from coupling effects in the interaction of the modes of SPs, consequently resulting in a large absorption cross section [66][67][68]. It has been reported that the amplitudes of such EM enhancements are mainly related to the space of the gap and numbers of plasmonic metallic units.…”

Hot electron photodetection with spectral selectivity in the C-band using a silicon channel-separated gold grating structure

“…Plasmonic nanostructures have received extensive attention due to their ability to increase the harvesting of incident light from free space and concentrate electromagnetic energy to nanoscale volumes through the excitation of surface plasmons (SPs). With this outstanding property, plasmonic nanostructures have been widely used to enhance the performance of optoelectronic devices, such as photocatalysis devices [1,2], solar energy harvesting devices [3,4], lasing devices [5,6], imaging devices [7], monitoring devices [8], and photodetectors [9][10][11][12][13][14]. SP-based photodetectors generally have higher external quantum efficiencies and responsivities than conventional photodetectors because of the enhanced light absorption and the ability to generate hot electrons through the nonradiative decay of SPs [15,16].…”