  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.
