0000000000810713
AUTHOR
Samuli Heiskanen
Superconducting tunnel junction fabrication on three-dimensional topography based on direct laser writing
Superconducting junctions are widely used in a multitude of applications ranging from quantum information science and sensing to solidstate cooling. Traditionally, such devices must be fabricated on flat substrates using standard lithographic techniques. In this study, we demonstrate a highly versatile method that allows for superconducting junctions to be fabricated on a more complex topography. It is based on maskless direct laser writing and two-photon lithography, which allows writing in 3D space. We show that high-quality normal metal–insulator–superconductor tunnel junctions can be fabricated on top of a 20-lm-tall three-dimensional topography. Combined with conformal resist coating m…
Intregrating metallic wiring with three-dimensional polystyrene colloidal crystals using electron-beam lithography and three-dimensional laser lithography
We demonstrate a method to fabricate narrow, down to a few micron wide metallic leads on top of a three-dimensional colloidal crystal self-assembled from polystyrene (PS) nanospheres of diameter 260 nm, using electron-beam lithography. This fabrication is not straightforward due to the fact that PS nanospheres cannot usually survive the harsh chemical treatments required in the development and lift-off steps of electron-beam lithography. We solve this problem by increasing the chemical resistance of the PS nanospheres using an additional electron-beam irradiation step, which allows the spheres to retain their shape and their self-assembled structure, even after baking to a temperature of 16…
Controlling thermal conductance using three-dimensional phononic crystals
Controlling thermal transport at the nanoscale is vital for many applications. Previously, it has been shown that this control can be achieved with periodically nanostructured two-dimensional phononic crystals for the case of suspended devices. Here, we show that thermal conductance can also be controlled with three-dimensional phononic crystals, allowing the engineering of the thermal contact of more varied devices without the need for suspension in the future. We show the experimental results obtained at sub-Kelvin temperatures for two different period three-dimensional crystals and for a bulk control structure. The results show that the conductance can be enhanced with the phononic cryst…
Nanofabrication on 2D and 3D Topography via Positive‐Tone Direct‐Write Laser Lithography
Direct laser writing (DLW) lithography using two‐photon absorption is a powerful technique mostly used for fabrication of complex structures in micro‐ and nanoscale, by photopolymerizing a negative‐tone resist. In contrast, in this study it is demonstrated that DLW is also well suited for fabricating nano‐ to microscale metallic structures using lift‐off and a positive‐tone photoresist. It is shown first that versatile, fast and large area fabrication is possible on flat two‐dimensional insulating substrates, and an expression for how the line width varies with the scanning speed is derived, with excellent agreement with the experiments. Even more interestingly, a unique application for the…
Fabrication of a gap structure for near-field heat transfer
Tutkimuksessa kehitettiin kahden vaiheen valmistusprosessi rakorakenteen valmistamiseen, jossa on metallista valmistetut johdot. Tämä rakorakenne on tarkoitettu lähikentän lämmönsiirtymisen mittaamiseen. Valmistus tehtiin pääasiassa 3D-litografialla käyttämällä Nanoscribe Photonic Professional -järjestelmää. Valmistukseen sisältyi myös ALD (Atomic Layer Deposition), metallipäällystys höyrystämällä, lift-off ja ionisuihkujyrsintä. Valmistettu rakenne koostuu kahdesta suorakulmaisesta särmiöstä lähellä toisiaan, jotka muodostavat ripustetun yhdensuuntaisten tasojen geometrian. Särmiöiden päälle tehdyt metalloinnit koostuivat ohuesta kultalangasta, joka voi toimia resistiivisenä lämpömittarina…
Superconducting tunnel junction fabrication on three-dimensional topography via direct laser writing
Superconducting junctions are widely used in multitude of applications ranging from quantum information science and sensing to solid-state cooling. Traditionally, such devices must be fabricated on flat substrates using standard lithographic techniques. In this study, we demonstrate a highly versatile method that allows for superconducting junctions to be fabricated on a more complex topography. It is based on maskless direct laser writing (DLW) two-photon lithography, which allows writing in 3D space. We show that high-quality normal metal-insulator-superconductor (NIS) tunnel junctions can be fabricated on top of a 20 $\mu$m tall three-dimensional topography. Combined with more advanced r…