Local anodic oxidation of superconducting NbN thin films by an atomic force microscope

Abstract

A local anodic oxidation technique has been applied to create oxidized nanowires on superconducting NbN thin films using an atomic force microscope (AFM) with a conductive probe. The AFM surface topography shows that both the width and height of the oxidized nanowires increase with increasing applied probe voltage under a certain relative humidity and a probe scan rate. The resistances of the NbN microbridges with and without an oxidized nanowire crossing were measured, and the results indicate that the oxidized nanowires with height of more than 8 nm are fully oxidized. The R–T and I–V characteristics of the NbN microbridges with the oxide wire of less than 8 nm were also obtained and analyzed. Methods for fabricating devices such as superconducting single photon detectors and superconducting hot electron bolometer mixers using this technology are discussed.

Fabrication of Nb Superconducting Nanowires by Nanoimprint Lithography

“…Several nanofabrication techniques have been used in SNSPDs fabrication. These include e-beam lithography (EBL) [1][2][3][4][5][6][7][8][9][10][11], focused ion beam (FIB) [13], and local oxidation with an atomic force microscope (AFM) [14,15]. However, these techniques usually require expensive equipments, and are time consuming for fabricating devices with large active area and, particularly for making the multi-element devices.…”

Fabrication of superconducting NbN meander nanowires by nano-imprint lithography

“…The superconducting nanowire single photon detector (SNSPD) has attracted extensive attention since 2001 when Gol'tsman et al showed first that the superconducting NbN nanowire made from ultra-thin NbN film could achieve single photon detection. [1,2] In most reported works on SNSPD, the devices were fabricated by using electron beam lithography (EBL), [3] although some other techniques such as focused ion beam (FIB) [4] and atomic force microscope (AFM) [5,6] were employed too. However, the EBL process requires expensive equipment and cannot meet the low cost and high efficiency requirement for mass production.…”