Large-format platinum silicide microwave kinetic inductance detectors for optical to near-IR astronomy

TL;DR

This paper reports on the development of large-format platinum silicide MKID arrays for optical and near-IR astronomy, achieving higher uniformity, better spectral resolution, and improved performance over previous titanium nitride-based arrays.

Contribution

Introduction of platinum silicide as a material for MKID arrays, leading to enhanced uniformity, higher pixel yield, and superior spectral resolution compared to traditional TiN arrays.

Findings

Higher uniformity and pixel yield in PtSi MKID arrays.

Demonstrated improved spectral resolution with PtSi arrays.

Elimination of hot pixel effects in PtSi MKIDs.

Abstract

We have fabricated and characterized 10,000 and 20,440 pixel Microwave Kinetic Inductance Detector (MKID) arrays for the Dark-speckle Near-IR Energy-resolved Superconducting Spectrophotometer (DARKNESS) and the MKID Exoplanet Camera (MEC). These instruments are designed to sit behind adaptive optics systems with the goal of directly imaging exoplanets in a 800-1400 nm band. Previous large optical and near-IR MKID arrays were fabricated using substoichiometric titanium nitride (TiN) on a silicon substrate. These arrays, however, suffered from severe non-uniformities in the TiN critical temperature, causing resonances to shift away from their designed values and lowering usable detector yield. We have begun fabricating DARKNESS and MEC arrays using platinum silicide (PtSi) on sapphire instead of TiN. Not only do these arrays have much higher uniformity than the TiN arrays, resulting in higher pixel yields, they have demonstrated better spectral resolution than TiN MKIDs of similar design. PtSi MKIDs also do not display the hot pixel effects seen when illuminating TiN on silicon MKIDs with photons with wavelengths shorter than 1 um.