Plasmonic Films Can Easily Be Better: Rules and Recipes

Abstract

High-quality materials are critical for advances in plasmonics, especially as researchers now investigate quantum effects at the limit of single surface plasmons or exploit ultraviolet- or CMOS-compatible metals such as aluminum or copper. Unfortunately, due to inexperience with deposition methods, many plasmonics researchers deposit metals under the wrong conditions, severely limiting performance unnecessarily. This is then compounded as others follow their published procedures. In this perspective, we describe simple rules collected from the surface-science literature that allow high-quality plasmonic films of aluminum, copper, gold, and silver to be easily deposited with commonly available equipment (a thermal evaporator). Recipes are also provided so that films with optimal optical properties can be routinely obtained.

Raman spectroscopy: techniques and applications in the life sciences

“…Empirical values for the permittivity (or equivalently the complex refractive index) can be found tabulated in various references [53][54][55][56]. For an E in the visible region of the spectrum, the real part of (ω) will be negative, seen in Figure 6(a), resulting in rapid attenuation of the field through the material (as n = (ω) will have a significant imaginary component) at some characteristic length usually known as the skin-depth.…”

“…It should be noted that the absorption component is most important for near-field enhancement, and will typically dominate for smaller particle size. [53], [54], * [55], [56]) and a theoretical model from the appendix of Le and Etchegoin [59] (solid line). These plots also highlight the performance of silver and gold, with Im( (ω)) in Figure 6(b), which relates to the internal losses in the material, being closer to zero for silver than in gold.…”

Limitations of ultra-thin transparent conducting oxides for integration into plasmonic-enhanced thin-film solar photovoltaic devices

“…There is thus a clear need to improve the efficiency of thin-film devices further [6]. Recent developments in plasmonics theory promise new methods with great potential to enhance light trapping in thin-film PV devices [7][8][9][10][11][12][13][14]. To fully exploit these potential benefits offered by plasmonic-based devices, TCOs with high transmittance (low loss) and low enough resistivity are to be used as device top contacts.…”

“…To fully exploit these potential benefits offered by plasmonic-based devices, TCOs with high transmittance (low loss) and low enough resistivity are to be used as device top contacts. However, for current transparent conducting oxides (TCOs) to be successfully integrated into the novel proposed plasmonicenhanced PV devices, ultra-thin TCOs films are required [14]. For example, simulations by Vora et al showed a 19.65 % increase in short circuit current (J SC ) for nanocylinder patterned solar cell (NCPSC) in which the ITO layer thickness was kept at 10 nm to minimize the parasitic Ohmic losses and simultaneously act as a buffer layer while helping to tune the resonance for maximum absorption [14].…”

Surface‐enhanced Raman spectra on graphene

“…The fraction of transmitted light can be calculated from the absorbance of the incoming and outgoing light expressed as T = exp[−(μ i + μ o ) t], where μ i and μ o are the absorbance coefficients of the incoming and outgoing light, respectively, and t is the thickness of the silver or gold layer. Using available data [31,32] At last, the effect of the metal on dispersion of the G and 2D band was investigated ( Figure 5). A linear fit of the 2D peak position as a function of laser energy results to a slope of 98 cm −1 /eV for pristine graphene, 119 cm −1 /eV for gold covered, and 111 cm −1 /eV for silver-covered graphene, respectively.…”