[19p-C207-1~17] 11.4 Analog applications and their related technologies

[19p-C207-1] Large area and high quality NbTiN thin film deposition method on quartz substrate

〇Akira Kawakami¹, Soma Ando², Kodai Suzuki², Gen Komatsu³, Atsushi Saito², Masanori Takeda³, Hirotaka Terai¹, Yoshinori Terai⁴ (1.NICT, 2.Yamagata Univ., 3.Shizuoka Univ., 4.NAOJ)

Keywords:NbTiN, Nb, Tuning circuit

Superconducting SIS mixers have relatively large junction capacitances, and good tuning circuits are essential. Currently, the SIS mixer for the ALMA Telescope Band 10 uses a high quality NbTiN superconducting thin film deposited on a fused quatz substrate to fabricate a tuned circuit, and an excellent low noise receiver that is less than five times the quantum noise limit was realized. However, it is difficult to form high quality NbTiN thin films in large areas with good reproducibility. We propose a new NbTiN film deposition method using Nb buffer layers. The NbTiN thin film prepared by this method showed good DC characteristics of T_C=14.9 K, ρ20 K=89.9 μΩcm.