Flexible Plasmonics Using Aluminum and Copper Epitaxial Films on Mica

Abstract

We demonstrate here the growth of aluminum (Al), copper (Cu), gold (Au), and silver (Ag) epitaxial films on twodimensional, layered muscovite mica (Mica) substrates via van der Waals (vdW) heteroepitaxy with controllable film thicknesses from a few to hundreds of nanometers. In this approach, the mica thin sheet acts as a flexible and transparent substrate for vdW heteroepitaxy, which allows for large-area formation of atomically smooth, single-crystalline, and ultrathin plasmonic metals without the issue of film dewetting. The highquality plasmonic metal films grown on mica enable us to design and fabricate well-controlled Al and Cu plasmonic nanostructures with tunable surface plasmon resonances ranging from visible to the nearinfrared spectral region. Using these films, two kinds of plasmonic device applications are reported, including (1) plasmonic sensors with high effective index sensitivities based on surface plasmon interferometers fabricated on the Al/Mica film and (2) Cu/Mica nanoslit arrays for plasmonic color filters in the visible and near-infrared regions. Furthermore, we show that the responses of plasmonic nanostructures fabricated on the Mica substrates remain unaltered under large substrate bending conditions. Therefore, the metal-on-mica vdW heteroepitaxy platform is suitable for flexible plasmonics based on their bendable properties.

Promoting 2D Material Photodetectors by Optical Antennas beyond Noble Metals

“…Beyond the typical precious metals, such as Au, [115][116][117] Ag, [118] Pt, [119] Ir, [120] and Pd, [121] there also exist several non-precious metals manifesting pronounced plasmonic effects, including Al, [122,123] Cu, [124][125][126] In, [127] Mo, [128] Sn, [129] Mg, [130] Sb, [131] Cu-Ni alloy, [132] Ga-In alloy, [133] etc. With the advantage of much lower cost, these materials have provided promising alternatives for the optical engineering research of next-generation optoelectronic devices.…”

Bendable Silicene Membranes

“…In this scenario, bendable membranes will be the building block for applications such as strain sensors, wearable electronics, and photonics, flexible plasmonics, implantable robotic skin, etc. [2][3][4][5] A number of organic and inorganic materials have been mooted as candidates for flexible device integration, and 2D materials may play a key role in this respect as they offer robust mechanical properties, sustaining a high level of strain before fracturing, complemented by optical and electronic properties suitable for application in nano-photonics and -electronics. [6,7] Moreover, strain engineering has been shown to provide a great opportunity for 2D material-based functional applications taking advantage of mechanisms like electronic bandgap tuning, [8,9] exciton manipulation, [10,11] carrier mobility boosting [12][13][14] and piezoresistivity.…”

Ultrathin Titanium Nitride Epitaxial Structures for Tunable Infrared Plasmonics

“…Therefore, deposition of ultrathin metal films typically requires additional wetting layers, resulting in increased optical losses and other device compatibility issues . Therefore, special growth techniques, such as growth at cryogenic temperatures , or on special substrates, are necessary to prepare ultrathin metal films without wetting layers. In this aspect, TiN offers an excellent opportunity for epitaxial growth of metals on semiconductor or oxide substrates because they have a mixture of covalent and metallic bonding …”