Giant enhancement of silicon plasmonic shortwave infrared photodetection using nanoscale self-organized metallic films

Abstract

Many consumer technologies and scientific methods rely on photodetection of infrared light. We report a Schottky photodetector operating below silicon's band gap energy, through hot carrier injection from a nanoscale metallic absorber. Our design relies on simple CMOScompatible 'bottom up' fabrication of fractally nanostructured aluminium films. Due to the fractal nature of the nanostructuring, the aluminium films support plasmonically enhanced absorption over a wide wavelength range. We demonstrate two orders of magnitude improvements of responsivity, noise-equivalent-power, and detectivity as compared to bulk metal, over a broad spectral and angular range. We attribute this to momentum relaxation processes from the nanoscale fractal geometry. Specifically, we demonstrate a direct link between quantum efficiency enhancement and structural parameters such as perimeter to surface ratio. Finally, our devices also function as bulk refractive index sensors. Our approach is a promising candidate for future cost effective and robust short wave infrared photodetection and sensing applications.

Polarization-Insensitive Waveguide Schottky Photodetectors Based on Mode Hybridization Effects in Asymmetric Plasmonic Waveguides

“…To make a quantitative understanding of the mode evolution process, the eigenmode expansion (EME) methods are employed to describe the power transformation between the hybrid modes we were concerned about. We also made a comparison of the finite difference time domain (FDTD) method and the EME evaluation which is deduced by Equation (7), in which Ataper is the absorption rate in the first two tapers, and Am denotes the power coupled to mth modes at the end of the taper section (z = 0), nmi is the imaginary part of the mth mode effective refractive index, k0 is the wave vector and z is the position in the rectangular regions along the mode propagation direction (z axis): Inspired by the above mode analyses, a dual-layer modified taper was proposed to achieve high efficiency polarization-insensitive absorption in ultrathin and ultra-compact metal films. The operating principle of our proposed device is schematically depicted in Figure 5a.…”

“…To meet the rising demands in optical communication, light detection and ranging (LiDAR), and nonlinear photonics, photodetectors (PDs) operating on 1.55 µm and beyond are highly desired. With the development of all-silicon integration, Si Schottky PDs based on internal photoemission (IPE) effect [1][2][3][4][5][6][7] have drawn much interest and been demonstrated in several platforms in recent decades. In such IPE-based devices, incident photons are usually absorbed by metals or silicides, and then hot carriers are produced by Landau damping [8].…”

Ultra-broadband metamaterial absorbers from long to very long infrared regime

“…Initial MPAs normally consist of a three-layer structure that is known as a metal/ insulator/metal (MIM) configuration. Special absorbers with fixed absorption performance have great potential for a variety of important scientific and technical applications, including thermal emitters 12,13 , energy harvesting [14][15][16] and detection 17,18 .…”

CMOS-Compatible Broad-Band Hot Carrier Photodetection with Cu–Silicon Nanojunctions

“…Harvesting photoexcited, nonequilibrium “hot” carriers (HCs) in metallic nanostructures offers considerable potential for sub-bandgap photodetection, energy conversion, and selective photocatalysis. − In particular, the excitation of surface plasmon localized at a metal–semiconductor (M–S) interface is commonly considered as a promising pathway for boosting the efficiency of these systems. − Photons incident on the metal side of the M–S junction are absorbed by the free carriers, which can be greatly enhanced by plasmonic resonance. The excited carriers, that is, HCs, with sufficient energy to surmount the energy barrier can be ejected into the semiconductor contributing to the photocurrent.…”