Ion-beam Assisted Sputtering of Titanium Nitride Thin Films*

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

tunable and desirable properties is of high importance [1–3]. Polakovic et al. [4] have shown

that for niobium nitride, ion beam assisted sputtering (IBAS) reduces 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 IBAS to compare their superconducting critical temperature Tc as a function of thickness,

sheet resistance, and nitrogen flow rate. Electrical and structural characterizations were performed

by four-wire electric transport and X-ray diffraction measurements. Compared to the conventional

method of reactive sputtering, we have demonstrated a 10% increase in nominal critical temperature

and 33% reduced sensitivity to nitrogen flow for bulk 300 nm films using the IBAS technique without

noticeable variation in the lattice structure. In addition, the non-IBAS films thickness dependence

on Tc is consistent with associated weak localization or quantum size effects, while the IBAS films

show some deviations away from these models.

References:

[1] M. R. Vissers et al., Applied Physics Letters 97,232509 (2010).

[2] J. Gao et al., Applied Physics Letters 92, 152505 (2008).

[3] Y. L. et al., Materials Science and Engineering: A 445-446, 223 (2007).

[4] T. Polakovic et al., APL Materials 6, 76107 (2018).