Kavli Affiliate: Clarence Chang
| First 5 Authors: Timothy Draher, Tomas Polakovic, Juliang Li, Yi Li, Ulrich Welp
| Summary:
Titanium nitride is a material of interest for many superconducting devices
such as nanowire microwave resonators and photon detectors. Thus, controlling
the growth of TiN thin films with desirable properties is of high importance.
In previous work on niobium nitride, ion beam-assisted sputtering (IBAS)
reduced nitrogen sensitivity during deposition in tandem with an increase in
nominal critical temperature. We have deposited thin films of titanium nitride
by both, the conventional method of DC reactive magnetron sputtering and the
IBAS method and compare their superconducting critical temperatures Tc as
functions of thickness, sheet resistance, and nitrogen flow rate. We perform
electrical and structural characterizations by electric transport and X-ray
diffraction measurements. Compared to the conventional method of reactive
sputtering, the IBAS technique has demonstrated a 10% increase in nominal
critical temperature and 33% reduced sensitivity to nitrogen flow, without
noticeable variation in the lattice structure. Additionally, we explore the
behavior of superconducting Tc in ultra-thin films. Trends in films grown at
high nitrogen concentrations follow predictions of mean-field theory in
disordered films and show suppression of superconducting Tc due to geometric
effects, while nitride films grown at low nitrogen concentrations strongly
deviate from the theoretical models.
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