Horn-Coupled, Commercially-Fabricated Aluminum Lumped-Element Kinetic Inductance Detectors for Millimeter Wavelengths

TL;DR

This paper presents the design, fabrication, and testing of horn-coupled aluminum LEKIDs optimized for 150 GHz CMB observations, demonstrating high yield, robust multiplexing, and competitive sensitivity.

Contribution

It introduces a commercially-fabricated, scalable LEKID array with high yield and sensitivity for millimeter-wave CMB studies, using standard photolithography.

Findings

Yield across arrays is 91%.

Noise-equivalent temperature is approximately 26 μK√s.

Multiplexing scheme is robust and scalable.

Abstract

We discuss the design, fabrication, and testing of prototype horn-coupled, lumped-element kinetic inductance detectors (LEKIDs) designed for cosmic microwave background (CMB) studies. The LEKIDs are made from a thin aluminum film deposited on a silicon wafer and patterned using standard photolithographic techniques at STAR Cryoelectronics, a commercial device foundry. We fabricated twenty-element arrays, optimized for a spectral band centered on 150 GHz, to test the sensitivity and yield of the devices as well as the multiplexing scheme. We characterized the detectors in two configurations. First, the detectors were tested in a dark environment with the horn apertures covered, and second, the horn apertures were pointed towards a beam-filling cryogenic blackbody load. These tests show that the multiplexing scheme is robust and scalable, the yield across multiple LEKID arrays is 91%, and the noise-equivalent temperatures (NET) for a 4 K optical load are in the range 26$\thinspace\pm6 \thinspace \mu \mbox{K} \sqrt{\mbox{s}}$.