Near Infrared Efficiency Enhancement of Silicon Photodiodes by Integration of Metal Nanostructures Supporting Surface Plasmon Polaritrons

Abstract

Recent years have witnessed a growing interest in detectors capable of detecting single photons in the near-infrared (NIR), mainly due to the emergence of new applications such as light detection and ranging (LiDAR) for, e.g., autonomous driving. A silicon single-photon avalanche diode is surely one of the most interesting and available technologies, although it yields a low efficiency due to the low absorption coefficient of Si in the NIR. Here, we aim at overcoming this limitation through the integration of complementary metal–oxide–semiconductor (CMOS) -compatible nanostructures on silicon photodetectors. Specifically, we utilize silver grating arrays supporting surface plasmons polaritons (SPPs) to superficially confine the incoming NIR photons and therefore to increase the probability of photons generating an electron-hole pair. First, the plasmonic silver array is geometrically designed using time domain simulation software to achieve maximum detector performance at 950 nm. Then, a plasmonic silver array characterized by a pitch of 535 nm, a dot width of 428 nm, and a metal thickness of 110 nm is integrated by means of the focused ion beam technique on the detector. Finally, the integrated detector is electro-optically characterized, demonstrating a QE of 13% at 950 nm, 2.2 times higher than the reference. This result suggests the realization of a silicon device capable of detecting single NIR photons, at a low cost and with compatibility with standard CMOS technology platforms.

Channel Nanoscaling of InGaZnO TFTs and Circuits via Focused Ion Beam

“…The working acceleration voltage that this equipment is optimized for is 35 kV, which transduces in implantation energy of 35 and 70 keV for single- and double-charged ions, respectively. The FIB patterning required careful optimization of beam parameters to prevent excessive ion implantation and damage to the underlying layer, specifically IGZO . The choice between Au and Ge ions was made based on considerations of patterning time, resolution, and potential contamination of the underlying layer.…”

“…The FIB patterning required careful optimization of beam parameters to prevent excessive ion implantation and damage to the underlying layer, specifically IGZO. 25 The choice between Au and Ge ions was made based on considerations of patterning time, resolution, and potential contamination of the underlying layer. Lighter ions, such as Ge, were advantageous in terms of smaller virtual source and beam spot diameter but came with a lower sputter yield, requiring longer patterning times at the same energy.…”

“…To the best of our knowledge, this is the shortest channel length ever reported for IGZO TFTs on a flexible substrate. While the employment of Ga ions prevents the contamination of the IGZO layer, further shortening of the channel can be achieved using ions like Ge and Au supplied by liquid metal alloy ion sources (LMAIS) which combine long-term stability and higher resolution patterning. − In this work, sub-100 nm ultrascaled IGZO TFTs and circuits on a free-standing polyimide foil are presented. The devices were fabricated by milling the metal contacts using Au + and Ge +2 ions, respectively.…”

Surface structured silver-copper bimetallic nanoparticles by irradiation of excimer laser pulses to bilayer thin films

“…Producing metallic nanostructures (NSs) is one interesting research field due to their unique optical properties that lead to their wide range of applications in enhanced spectroscopy, biosensors, cancer treatment, drug delivery and imaging, metamaterials, nonlinear optics, environmental protection, information technology, and energy production [1][2][3][4][5][6][7][8][9][10][11]. Surface plasmon resonance (SPR), localized surface plasmon resonance (LSPR), and surface-enhanced Raman scattering (SERS) based on NSs can be applied for sensing with a high sensitivity along with very high spectroscopic accuracy that brings them an excellent candidate for use in chemical and biomolecular sensing [12,13].…”