Ge-on-Si PIN-photodetectors with Al nanoantennas: The effect of nanoantenna size on light scattering into waveguide modes

Abstract

Metallic nanoantennas can be used to enhance the efficiency of optical device operation by re-distributing electromagnetic energy. Here, we investigate the effect of a random distribution of disc-shaped Al nanoantennas of different diameters deposited on Ge-on-Si PIN-photodetectors on the wavelength-dependent responsivity. We compare our experimental results to simulations and find that the largest responsivity enhancement is obtained for wavelengths that correspond to energies at or below the bandgap energy of Ge. We argue that this is the result of antenna-mediated scattering of light into waveguide modes within the Ge-on-Si PIN-photodetectors, which is effectively influenced by nanoantenna size, and we discuss a possible application of the concept for integrated biosensing.

Optofluidic sensor system with Ge PIN photodetector for CMOS-compatible sensing

“…Absorption within the COC material used for the microfluidic waveguides does not limit the sensing capabilities: our simple sensor was able to distinguish between fluids with different refractive indices flowing over the detector. Within the scope of future work the detector will be equipped with a plasmonic nanohole array combining high-sensitivity sensing using LSPR (Augel et al 2016) and detection within one device.…”

“…This proof-of-concept of a simplistic refractive index sensor can be used as a platform for further improved CMOS-devices, which are e.g. equipped with localized surface plasmon resonance (LSPR) based sensing approaches using metallic nanostructures (Canalejas-Tejero et al 2014;Augel et al 2016;Fischer et al 2016). The platform even offers the feasibility of the complex flow-through instead of the classical flow-over LSPR sensing unit approach (Escobedo et al 2010).…”

Photonic-Plasmonic Mode Coupling in Nanopillar Ge-On-Si Pin Photodiodes

“…collective excitations of the free electron gas within the nanostructures, enable local electromagnetic field enhancement at the nanoscale [1]. This has seen wide applications ranging from biosensing [2,3], in which the sensitivity of the LSP properties to changes in the refractive index induced by analyte-ligand binding events is exploited, and wavelength-selective absorption enhancement in solar cells [4], bulk detectors [5] as well as nanoscale photodetectors [6]. LSPs can be utilized to focus incident light into nanoscale semiconductor volumes.…”

Optimization of Optical Nanoantenna Based on Structures Chiral Photonic Crystal

“…In this paper, we will study an optical nanoantenne based on dielectric materials, using a 2D CPC chiral photonic crystal structure [5][6][7][8][9][10][11], simulation allowing the plots of the radiation patterns of the adopted model. Then, we will introduce some modifications on the physical parameters of this structure in order to visualize its energy in emission, while evaluating its characteristic parameters and able to determine them; and thus compare the results obtained.…”

“…We propose here to transpose the concept of antenna to the scale of the optics of the visible. In this case, the reduction of the scales imposes the realization of submicron structures, baptized nanoantennes [1][2][3][4][5]. The latter aim here to act as a relay between the near -field spaces (nano -sources and nanocollectors) and far -field (propagating waves) for the localized emission or reception of light.…”