MKIDs are a class of superconducting detector with high sensitivity, straightforward scalability, and inherent energy resolution. The applications for Optical MKIDs include astronomy, dark matter detection, photonic quantum computing, and biological process imaging. To motivate greater use in these applications, improvements to MKID yield and uniformity at the array scale, detection efficiency, dark counts, and resolving power are required. This dissertation details a variety of detector designs towards these ends. First, the performance of several styles of phonon blocking architectures is discussed: superconducting bilayers, polymer suspended inductors, and air-suspended inductors. Next, the characterization of the dark count rate of a large-format MKID array is presented, with some investigation of the sources of this background. Finally, a large-format array is presented which made improvements to the yield, resonator quality factor, and quantum efficiency of the previous state-of-the-art optical MKID camera. This includes the first incorporation of anti-reflection coatings on an MKID array of this size. These explorations will help inform further development of optical MKID arrays for a variety of science goals.
The non-homogeneity in the critical temperature
Tc of an Microwave Kinetic Inductance Detector (MKID) could be caused by non-uniformity in the deposition process of the thin superconducting film. This produces low percent yield and frequency collision in the readout of the MKIDs. Here, we show the homogeneity that offers Atomic Layer Deposition (ALD). We report an improvement of up to a factor of 50 in the fractional variation of the
Tc for TiN MKIDs fabricated with Atomic Layer Deposition in comparison with MKIDs fabricated with sputtering. We measured the critical temperature of 48 resonators. We extracted the
Tc of the MKIDs by fitting the fractional resonance frequency to the complex conductivity of their resonators. We observed uniformity on the critical temperature for MKIDs belonging to the same fabrication process, with a maximum change in the
Tc of 60 mK for MKIDs fabricated on different wafers.