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Fabrication of Hyperbolic Metamaterials using Atomic Layer Deposition

Project type: Ph.d project
Project responsible: Evgeniy Shkodin
Supervisors: Andrei Lavrinenko, Flemming Jensen
Partners involved: DTU Fotonik, DTU Danchip

Project Description

Recent years have shown an explosive interest in the physics of hyperbolic metamaterials (HMMs). Electrodynamically HMMs are described by a dielectric permittivity tensor (ε) with components of opposite signs (e.g. εx=εy<0, εz>0). In such media the unusual hyperbolic dispersion relation supports propagating waves with anomalously large wave vectors. This and related phenomena give rise to a multitude of exotic physical effects and promising applications. Examples include broadband spontaneous emission enhancement, far-field subwavelength imaging (so-called hyperlensing) and anomalous heat transfer capabilities. From the fabrication standpoint, HMMs turn out to be deceptively simple: a typical geometry consists of a repeated basic metal-dielectric bilayer stack or a lattice of metallic nanowires embedded in a dielecric matrix. However, for the salient HMM properties to be pronounced, ultrathin, nanometer-scale thicknesses are required.
The required high-quality ultrathin layers (around 10 nm) can be fabricated using atomic layer deposition (ALD). ALD is a cyclic self-limiting thin film deposition technology allowing molecule level thickness control. As the deposition relies on a surface reaction, conformal pinhole free films can be deposited.
The main challenge of implementation of ALD processing for HMM fabrication is the requirement for depositing alternating layers of metals (Ag, Cu, W) and dielectric spacers (alumina, titania, silica) . Required thicknesses are in the range 5-15 nm for metals and 10-20 nm for dielectrics (oxides).

Publications

Experimental Demonstration of Effective Medium Approximation Breakdown in Deeply Subwavelength All-Dielectric Multilayers

Zhukovsky, S., Andryieuski, A., Takayama, O., Shkondin, E., Malureanu, R., Jensen, F., & Lavrinenko, A. (2015). Experimental Demonstration of Effective Medium Approximation Breakdown in Deeply Subwavelength All-Dielectric Multilayers. Physical Review Letters, 115(17), 177402 LINK

Procces flow

Fabrication of High Aspect Ratio TiO₂ and Al₂O₃ Nanogratings by Atomic Layer Deposition

Shkondin, E., Takayama, O., Lindhard, J., Larsen, P., Mar, M., Jensen, F. & Lavrinenko, A. (2016). Fabrication of high aspect ratio TiO₂ and Al₂O₃ nanogratings by atomic layer deposition. Journal of Vacuum Science and Technology A, 34, 031605 (2016) LINK

Procces flow

Name of publication3 made in this project

Reference and link to the publication

Link to process flow