Effect of Proximity in Arrays of Plasmonic Nanoantennas on Hot Spots Density: Degenerate Semiconductors vs. Conventional Metals

Using rigorous finite element electromagnetic calculations, we study the performance of a localized surface plasmons resonance array infrared sensor, from an uncommon perspective, by analyzing electromagnetic hot spots density. We show that the hot spots density strongly depends on near-field interaction between plasmonic nanoantennas. We provide important theoretical evidence that the degree of the interaction depends on both material and geometrical properties of an array. To this end, we consider arrays of conventional metal (CM) and plasmonic transparent conducting oxide (TCO) at different nanoantennas density. We establish that a single CM nanoantenna has higher field intensity enhancement than a TCO counterpart. On the other hand, an array of TCO nanoantennas provides 30 times larger density of the hotspots and 15 times higher signal-to-noise ratio, as compared to a CM array.