Plasmonic Aluminium Metamaterials (PAlMs): Self-

Assembled Hyperbolic Metamaterials In The Deep UV

Serena Skov Campbell Kings College London 2015

Overview

• Why are we interested in metamaterials in the deep UV?

• Fabrication methods of aluminium metamaterials

• Preliminary results for electrodeposited thin film aluminium on gold substrates

Metamaterials in the UV• Biological detection / UV-SERS• Amino acids absorb in the UV – DNA, RNA • Resonant enhancement + surface enhancement• Lower fluorescent background in the UV• Reproducible, label-free, real-time detection• Increased sensitivity

• Observing and controlling photochemical reactions

UV-SERS spectral data for Adenine.

Aluminium as a plasmonic material in the UV

• Q factor comparison between various metallic materials• Long term sustainability of samples (compared to fx silver)

Fabrication of Aluminium by electrodeposition • Basic experimental setup• Nernst equation• Ionic Liquid – Acidic AlCl3 solution

Reduction of AlCl3

Template based fabrication of Aluminium• AAO template• Controlled aspect ratio and morphology

AAO template structure Electrodeposited Al nanorods (Oltean et. al, 2011)

Height control of electrodeposited nanorods

1. Nucleation pulse (0.4V vs. Al3+/Al)2. Slight fluctuations due to imperfect

conductivity. 3. Pores are filled: surface area increases4. Thin film deposition

Thin film ED of Aluminium: Results

• ED of Al onto gold substrates• Nucleation effects due to impurities on substrate / deposition time

20x20um area of Au with 23s deposited Al at 0.5V vs. Ref.

Thin film deposition of Aluminium on a gold substrate

Thin film ED of Aluminium: Results

Deposited Aluminium on gold substrate - Roughness RMS 2.18

Gold substrate - Roughness RMS 1.65 Approx. 10nm Al for 23s deposition. Dep. rate = 0.43nm/s

• Initial results of surface roughness and deposition rate: AFM

Future research

• Morphology investigations: Aluminium nanodots, nanorings and nanocones.

Thank you for listening

Contact: Serena.Campbell@kcl.ac.uk

Current work• Solution contamination issue• Measure deposition rates on ITO substrates• Optimise the setup to limit variables • AAO on gold substrates – why is this an issue?

• https://www.youtube.com/watch?v=UHMIWk2iIdI