Embedding Plasmonic Nanostructure Diodes Enhances Hot Electron Emission

Abstract

When plasmonic nanostructures serve as the metallic counterpart of a metal-semiconductor Schottky interface, hot electrons due to plasmon decay are emitted across the Schottky barrier, generating measurable photocurrents in the semiconductor. When the plasmonic nanostructure is atop the semiconductor, only a small percentage of hot electrons are excited with a wavevector permitting transport across the Schottky barrier. Here we show that embedding plasmonic structures into the semiconductor substantially increases hot electron emission. Responsivities increase by 25× over planar diodes for embedding depths as small as 5 nm. The vertical Schottky barriers created by this geometry make the plasmon-induced hot electron process the dominant contributor to photocurrent in plasmonic nanostructure-diode-based devices.

Silicon-based broadband antenna for high responsivity and polarization-insensitive photodetection at telecommunication wavelengths

“…Furthermore, the large area of Schottky junction in deep trenches is a very important feature for increasing the conversion efficiency of active antenna-based photodetection. In previous study, the vertical Schottky interfaces in nanoantenna-based devices were demonstrated having a great contribution to the photo-response 22 . Accordingly, the Au/Si interfaces in the deep trenches sufficiently construct the 3D Schottky interfaces with large area on both the surface and vertical sides of the DTTM structures.…”

Harvesting the loss: surface plasmon-based hot electron photodetection

“…For instance, the recent investigation that uses plasmonic tips to adiabatically compress the SPPs, producing hot electrons with momentum perpendicular to the interface, demonstrated a greatly enhanced efficiency [95]. 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].…”

Metal-insulator-semiconductor heterostructures for plasmonic hot-carrier optoelectronics

“…The excitation profile, as well as the energy distribution of hot-electrons, is correlated with the intensity of the electric field [33]. (ii) hot-carriers are emitted with a particular direction, or momentum, depending on the crystal structure [4,21,34] and electric field. (iii) If these energetic electrons arrive at the MS interface with enough momentum, they can be injected or tunnel to the adjacent semiconductor over/through the barrier (Φ b ), generating a photocurrent.…”

“…If these excited carriers are collected before thermalization occurs by internal photoemission (typically a ps-window interval) [5], they can result in a photocurrent with an spectral response tunable by metal nanostructuring, enabling therefore functionalities beyond those resulting from band-to-band absorption in semiconductors. This is appealing for applications such as light-energy harvesting (photocatalysis [6][7][8][9][10][11][12] and photovoltaics [13][14][15][16][17][18]), and photodetection [19][20][21][22][23][24][25][26][27][28]. Initially focused in the area of photocatalysis and photochemistry, research in plasmonic hot-electron devices has recently seen significant advances in the area of solid state photodetection and photovoltaic devices, based on a Schottky metal-semiconductor (MS) architecture.…”