Silicon-Based Optoelectronics Enhanced by Hybrid Plasmon Polaritons: Bridging Dielectric Photonics and Nanoplasmonics

Effect of laser fluence on the optoelectronic properties of nanostructured GaN/porous silicon prepared by pulsed laser deposition

In this study, the fabrication of nanostructured GaN/porous Si by pulsed laser deposition (PLD) was demonstrated. The porous silicon was prepared using laser-assisted electrochemical etching (LAECE). The structural, optical, and electrical properties of GaN films were investigated as a function of laser fluence. XRD studies revealed that the GaN films deposited on porous silicon were nanocrystalline, exhibiting a hexagonal wurtzite structure along the (100) plane. Spectroscopic property results revealed that the photoluminescence PL emission peaks of the gallium nitride over porous silicon (GaN/PSi) sample prepared at 795 mJ/mm2 were centered at 260 nm and 624 nm. According to topographical and morphological analyses, the deposited film consisted of spherical grains with an average diameter of 178.8 nm and a surface roughness of 50.61 nm. The surface of the prepared films exhibited a cauliflower-like morphology. The main figures of merit of the nanostructured GaN/P-Si photodetectors were studied in the spectral range of 350-850 nm. The responsivity, detectivity, and external quantum efficiency of the photodetector at 575 nm under - 3 V were 19.86 A/W, 8.9 × 1012 Jones, and 50.89%, respectively. Furthermore, the photodetector prepared at a laser fluence of 795 mJ/mm2 demonstrates a switching characteristic, where the rise time and fall time are measured to be 363 and 711 μs, respectively.

Proposal and Design of Flexible All-Polymer/CIGS Tandem Solar Cell

Tandem solar cells (TSCs) have attracted prodigious attention for their high efficiency, which can surmount the Shockley-Queisser limit for single-junction solar cells. Flexible TSCs are lightweight and cost-effective, and are considered a promising approach for a wide range of applications. In this paper, a numerical model, based on TCAD simulation, is presented to assess the performance of a novel two-terminal (2T) all-polymer/CIGS TSC. To confirm the model, the obtained simulation results were compared with standalone fabricated all-polymer and CIGS single solar cells. Common properties of the polymer and CIGS complementary candidates are their non-toxicity and flexibility. The initial top all-polymer solar cell had a photoactive blend layer (PM7:PIDT), the optical bandgap of which was 1.76 eV, and the initial bottom cell had a photoactive CIGS layer, with a bandgap of 1.15 eV. The simulation was then carried out on the initially connected cells, revealing a power conversion efficiency (PCE) of 16.77%. Next, some optimization techniques were applied to enhance the tandem performance. Upon treating the band alignment, the PCE became 18.57%, while the optimization of polymer and CIGS thicknesses showed the best performance, reflected by a PCE of 22.73%. Moreover, it was found that the condition of current matching did not necessarily meet the maximum PCE condition, signifying the essential role of full optoelectronic simulations. All TCAD simulations were performed via an Atlas device simulator, where the light illumination was AM1.5G. The current study can offer design strategies and effective suggestions for flexible thin-film TSCs for potential applications in wearable electronics.

Sodium-Based Cylindrical Plasmonic Waveguides in the Near-Infrared

Subwavelength optical field confinement and low-loss propagation are of great significance for compact photonic integration. However, the field confinement capability of plasmonic devices is always accompanied by the inherent Ohmic loss. Although recent studies have shown that sodium (Na) exhibits lower loss than noble metals in the near-infrared band, the field confinement ability has not been adequately assessed. Meanwhile, the high chemical reactivity of Na should be regulated for practical application. Two dielectric-coated Na nanowires, consisting of cylindrical Na nanowires with one or two dielectric layers as claddings, are proposed and investigated in this paper. Based on finite element calculations, we thoroughly study the modal fields and low-loss propagation properties of dielectric-coated Na nanowires. The results demonstrate that Na exhibits lower loss and stronger field confinement than the typical plasmonic material silver. These findings indicate the performance of plasmonic devices can be considerably improved by employing the metal Na compared with devices using noble metals, which may promote the applications in subwavelength photonic devices.