The performance of a plasmonic antireflection layer which can be utilized for deep-space radiationresistant GaSb solar cells is investigated numerically and experimentally. The layer consists of nanodots made by plasma etching of a GaSb substrate and subsequent physical vapor deposition of Ag nanoparticles on the nanodot tips, in a partially ordered configuration determined by the plasma energy level. This technique is readily applicable to patterning of silicon. We measure the substrate reflectivity and model the reflection and absorption of the substrates using the 3D finite difference time domain (FDTD) method, which are realistically imported as 3D layers from the scanning electron microscopy (SEM) images. The variation of the height of the Ag nanoparticles on top of the GaSb pillars shows that the plasmonic effect remarkably enhances the absorption. The presence of GaSb pillars enhances absorption and tunes the maximum absorption wavelength peak. 1. Introduction Design and fabrication of cost-effective and efficient photovoltaic solar cells are a challenging task. Generally, nonreflective substrates like silicon are used in solar cells. These kinds of substrates exhibit high absorption and trapping of light in the solar cell substrate. However, this enhancement is confined to a short range of wavelengths. To increase the operational bandwidth, the silicon substrate is textured using etchant. This method decreases the reflectivity of the silicon substrate to the level of 20% reflection [1] and even to 1% in the case of black Si made by dry plasma etching [2]. Noble metals exhibit plasmonic effects on the surface of semiconductors and can enhance the absorption cross-section at the active region of a device by several orders of magnitude. This plasmonic effect is the result of collective oscillation of free electrons in the nanostructures when illuminated by visible-IR light. The main condition to achieve plasmonic light enhancement is deposition on noble metals patterns and layers onto a substrate. Negative electric permittivity of gold or silver in the visible-IR range is required for a particle size smaller than the incident wavelength (i.e. , where is the particle size, and is the incident wavelength) to create strong light field enhancement in the closest vicinity of the nanoparticle [3–5]. Noble metal nanoparticles (NPs) deposited on patterned nanostructures have shown better enhancement of the absorption cross-section in several kinds of solar cells, due to the plasmonic effect, and have given birth to the new concept of plasmonic solar cell
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