Fabrication of superconducting NbN meander nanowires by nano-imprint lithography

Superconducting nanowire single photon detector (SNSPD), as a new type of superconducting single photon detector (SPD), has a broad application prospect in quantum communication and other fields. In order to prepare SNSPD with high performance, it is necessary to fabricate a large area of uniform meander nanowires, which is the core of the SNSPD. In this paper, we demonstrate a process of patterning ultra-thin NbN films into meander-type nanowires by using the nano-imprint technology. In this process, a combination of hot embossing nano-imprint lithography (HE-NIL) and ultraviolet nano-imprint lithography (UV-NIL) is used to transfer the meander nanowire structure from the NIL Si hard mold to the NbN film. We have successfully obtained a NbN nanowire device with uniform line width. The critical temperature (T_c) of the superconducting NbN meander nanowires is about 5 K and the critical current (I_c) is about 3.5 μA at 2.5 K.