Hybrid α -Ta/ β -Ta lumped element kinetic inductance detectors with photon noise limited sensitivity and stability

The terahertz (THz) band is of immense interest in astronomy as it encompasses significant energy generated following the Big Bang, offering critical insight into processes invisible in other bands, such as the earliest stages of planet, star, and galaxy formation. Kinetic inductance detectors (KIDs) have emerged as a formidable contender in the field of THz astronomy, attributed to their exceptional sensitivity and scalability. In this study, we introduce a kind of KIDs incorporating a lumped element (LE) resonator design, with inductors fabricated on β-Ta film and capacitors on α-Ta film. We characterize the noise of the hybrid α-Ta/β-Ta LEKIDs, achieving an optical noise equivalent power of 8.3 ± 5.7 × 10−19 W/Hz1/2, demonstrating high sensitivity. Additionally, the LEKIDs exhibited stability across multiple thermal cycles. The combination of high sensitivity and stability makes the hybrid LEKIDs promising for the stringent demands of THz astronomy.