Uniform non-stoichiometric titanium nitride thin films for improved kinetic inductance detector array

TL;DR

This paper reports on the fabrication of uniform sub-stoichiometric titanium nitride films for microwave kinetic inductance detector arrays, achieving high sensitivity and low noise, with potential for further performance improvements.

Contribution

It introduces a fabrication process for homogeneous TiN films with reduced critical temperature variation, enabling high-performance mKID arrays.

Findings

Critical temperature variation reduced to <25% across 2-inch wafer

Achieved sensitivity of 16 kHz/pW in 100 GHz band

Noise equivalent power of 3.6e-15 W/Hz^(1/2)

Abstract

We describe the fabrication of homogeneous sub-stoichiometric titanium nitride films for microwave kinetic inductance detector (mKID) arrays. Using a 6 inch sputtering target and a homogeneous nitrogen inlet, the variation of the critical temperature over a 2 inch wafer was reduced to <25 %. Measurements of a 132-pixel mKID array from these films reveal a sensitivity of 16 kHz/pW in the 100 GHz band, comparable to the best aluminium mKIDs. We measured a noise equivalent power of NEP = 3.6e-15 W/Hz^(1/2). Finally, we describe possible routes to further improve the performance of these TiN mKID arrays.