Molybdenum nanopillar arrays
Fabrication and engineering
Louis Maduro (TU Delft - QN/Conesa-Boj Lab, Kavli institute of nanoscience Delft)
Charles de Boer (Kavli institute of nanoscience Delft)
Marc Zuiddam (Kavli institute of nanoscience Delft, TU Delft - QN/Kavli Nanolab Delft)
Elvedin Memisevic (TU Delft - BUS/Quantum Delft, Kavli institute of nanoscience Delft)
Sonia Conesa-Boj (Kavli institute of nanoscience Delft, TU Delft - QN/Conesa-Boj Lab)
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Abstract
We report on the fabrication of molybdenum (Mo) nanopillar (NP) arrays with NP diameters down to 75 nm by means of deep-reactive ion etching at cryogenic temperatures. A variable-thickness Mo metal layer sputtered onto a Si3N4/Si substrate makes possible NPs with different lengths in a controllable manner. We demonstrate how our fabrication strategy leads to tunable cross-sections with different geometries, including hexagonal, cylindrical, square and triangular shapes, by using electron beam lithography on hydrogen silsesquioxane negative tone resist. To ensure well-defined facets and surfaces, we employ deep-reactive ion etching in a gas mixture of SF6 and O2 at cryogenic temperatures in an inductively coupled plasma reactive ion etching (ICP-RIE) system. These results represent an attractive route towards the realization of high-density Mo NP arrays for applications from nanoelectronics to quantum sensing and hydrogen evolution reaction catalysis.
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