Enhancement of Light Absorption in Silicon Nanowire Photovoltaic Devices with Dielectric and Metallic Grating Structures

Abstract

We report the enhancement of light absorption in Si nanowire photovoltaic devices with one-dimensional dielectric or metallic gratings that are fabricated by a damage-free, precisely aligning, polymer-assisted transfer method. Incorporation of a SiN grating with a Si nanowire effectively enhances the photocurrents for transverse-electric polarized light. The wavelength at which a maximum photocurrent is generated is readily tuned by adjusting the grating pitch. Moreover, the electrical properties of the nanowire devices are preserved before and after transferring the SiN gratings onto Si nanowires, ensuring that the quality of pristine nanowires is not degraded during the transfer. Furthermore, we demonstrate Si nanowire photovoltaic devices with Ag gratings using the same transfer method. Measurements on the fabricated devices reveal approximately 27.1% enhancement in light absorption compared to that of the same devices without the Ag gratings without any degradation of electrical properties. We believe that our polymer-assisted transfer method is not limited to the fabrication of grating-incorporated nanowire photovoltaic devices but can also be generically applied for the implementation of complex nanoscale structures toward the development of multifunctional optoelectronic devices.

Remote nongenetic optical modulation of neuronal activity using fuzzy graphene

“…S5 B and C). The UV-Vis spectrum for i-SiNW agrees well with previously reported results (32)(33)(34). The enhanced broadband absorption by NT-3DFG can be attributed to the increased light trapping by the densely packed out-of-plane 3DFG flakes, as this structure is synonymous to that of nanostructured silicon and carbon metamaterials (35)(36)(37).…”

Directly Probing Light Absorption Enhancement of Single Hierarchical Structures with Engineered Surface Roughness

“…Up to now, the evaluation of light absorption of single micro/nanowires relies either on indirect measurement or theoretical models, which can only provide qualitative values 28 – 35 . Experimental methods for probing light absorption such as monitoring the photocurrent generated within single wire devices are time-consuming and require complicated microelectrodes fabrication process 36 – 41 . In addition, we have shown that the real nanowire absorption deviates significantly from the theoretical prediction calling for caution in using these equations or simulation results.…”

Nanostructured photovoltaics

“…NWs are passive towards impurities present in the bulk, and hence can be fabricated from bulk materials with lower purity, reducing the cost [253]. They help in efficient light management in solar cells through two main methods: (a) by providing spectrally selective improved scattering of light and increased absorption through resonant modes [254][255][256][257][258][259][260][261] and (b) by enhancing charge carrier dynamics through increased efficiency of charge carrier generation and collection [253,262]. Further, theoretical limit for NW solar cells can reach up to 42% [263], though some have argued that such high performance cannot be attained due to contact and surface recombination [264].…”