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0Quasi-two dimensional gold films for plasmonic and optoelectronic applications
D.I. Yakubovsky1, M.S. Mironov1, A.S. Slavich1, D.V. Grudinin1, I.S. Kazantsev1, G.A. Ermolaev2, A.V. Arsenin1,2, V.S. Volkov2
1- Center for Photonics and 2D Materials, Moscow Institute of Physics and Technology, Russia 2- Emerging Technologies Research Center, XPANCEO, Dubai Investment Park First, Dubai, United Arab
Emirates
Ultrathin metal films are a platform for a range of applications, from flexible transparent electrodes to plasmonic interconnects. Due to their small thickness (<10 nm) these films demonstrate high optical transmittance in visible spectrum and mechanical flexibility. Growth of high-quality ultrathin or quasi-two-dimensional (2D) plasmonic (Au, Ag, Cu) films requires the use of seed, adhesion layers and ultrasmooth surfaces [1]. However, to provide really continuous metal films growth the use of additional wetting 2D layers and methods of 2D materials growth can be applied. As example, addition of molybdenum disulfide (MoS2) underlayers resulted in growth of continuous ultrathin gold films with high plasmonic and electric response [2]. Morphological homogeneity and smoothness of substrate surface affect the quality of ultrathin or quasi-2D metals, since they replicate morphology of the surface. The introduction of ultrathin metal films in different applications is restricted by the choice of wetting layers and substrates. Thus, the development of novel methods for production of ultrathin films are required.
Here, we demonstrate fabrication of ultrasmooth high-quality ultrathin gold films of thicknesses below 10 nm and performed their comprehensive study using atomic-force and scanning electron microscopy, ellipsometry, optical transmission and sheet resistance measurements, scanning near-field optical microscopy. We have confirmed surface plasmon polaritons propagation, as shown in Fig. 1a, and high local optical response [2]. In addition, we developed the method for the growth of quasi-2D gold films providing one of the best optoelectronic performance in terms of conductivity (10 Q/sq) and transparency (80%) (see Fig. 1b). The obtained results are crucial for growth and characterization of ultrathin metals in their potential use in optoelectronics and photonics applications.
Figure 1. (a) Scanning near-field optical microscopy image of surface plasmon polariton propagation in ultrathin gold film. (b) Photo image of the produced sample with transparent conductive ultrathin film.
[1] R.A. Maniyara, D. Rodrigo, R. Yu, J. Canet-Ferrer, D.S. Ghosh, R. Yongsunthon, et al, Tunable plasmons in ultrathin metal films, Nature Photonics, 13, 328-333 (2019).
[2] D.I. Yakubovsky, D.V. Grudinin, G.A. Ermolaev, et al, Optical nanoimaging of surface plasmon polaritons supported by ultrathin metal films, Nano Letters, 23, 9461-9467 (2023).
