Development of THz Waveguide NbTiN HEB Mixers

Jiang, Ling; Shiba, Shoichi; Shimbo, K.; Sakai, Nami; Yamakura, T.; Sugimura, M.; Ananthasubramanian, P. G.; Maezawa, Hiroyuki; Irimajiri, Yoshihisa; Yamamoto, Satoshi

doi:10.1109/tasc.2009.2019071

Cited by 15 publications

(15 citation statements)

References 11 publications

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“…NbTiN thin films are widely investigated as candidates for many superconducting devices, including nanowire superconducting single photon detectors (SNSPD), [1][2][3][4] hot electron bolometer (HEB) mixers, [5][6][7] superconductor-insulatorsuperconductor (SIS) devices in the THz band, [8][9][10] and coplanar waveguide (CPW) superconducting resonators. [11] Unlike NbN films, the introduction of the third element can locally modify the atomic binding energy, leading to electronic structure and crystal lattice modifications.…”

Section: Introductionmentioning

confidence: 99%

High quality NbTiN films fabrication and rapid thermal annealing investigation*

Ge¹,

Jin²,

Song³

2019

Chinese Phys. B

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NbTiN thin films are good candidates for applications including single-photon detector, kinetic inductance detector, hot electron bolometer, and superconducting quantum computing circuits because of their favorable characteristics, such as good superconducting properties and easy fabrication. In this work, we systematically investigated the growth of high-quality NbTiN films with different thicknesses on Si substrates by reactive DC-magnetron sputtering method. After optimizing the growth conditions, such as the gas pressure, Ar/N2 mixture ratio, and sputtering power, we obtained films with excellent superconducting properties. A high superconducting transition temperature of 15.5 K with narrow transition width of 0.03 K was obtained in a film of 300 nm thickness with surface roughness of less than 0.2 nm. In an ultra-thin film of 5 nm thick, we still obtained a transition temperature of 7.6 K. In addition, rapid thermal annealing (RTA) in atmosphere of nitrogen or nitrogen and hydrogen mixture was studied to improve the film quality. The results showed that T c and crystal size of the NbTiN films were remarkably increased by RTA. For ultrathin films, the annealing in N2/H2 mixture had better effect than that in pure N2. The T c of 10 nm films improved from 9.6 K to 10.3 K after RTA in N2/H2 mixture at 450 °C.

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Section: Introductionmentioning

confidence: 99%

High quality NbTiN films fabrication and rapid thermal annealing investigation*

Ge¹,

Jin²,

Song³

2019

Chinese Phys. B

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“…Niobium nitride (NbN) has recently become a material of interest in the fabrication of tunnel junctions, superconducting nanowire single-photon detectors (SNSPD), hot-electron bolometers (HEB), and so on [1][2][3][4][5][6]. In those applications, the common features sought for NbN films are a high superconducting critical temperature (T c ), a large critical current density, and a low normal-state resistivity (R N ).…”

Section: Introductionmentioning

confidence: 99%

Improvement of the superconducting properties of NbN thin film on single-crystal silicon substrate by using a TiN buffer layer

Zhang

et al. 2013

Supercond. Sci. Technol.

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Thin superconducting NbN film on silicon substrate is a promising material for use in some ultrasensitive sensors and detectors, such as the hot-electron bolometer mixer and the superconducting nanowire single-photon detector. Due to the large mismatch between NbN film and Si substrate, the NbN film has a lower critical temperature than NbN film on MgO substrate. TiN has been experimentally verified as a good buffer layer due to having the same face-centered-cubic crystallite structure as and a lattice constant close to that of the NbN film, i.e. the critical temperatures of NbN films (5-20 nm thickness) on TiN buffered silicon are about 1-3 K higher than those of NbN/Si. Such improvement can be ascribed not only to the reduction of the interface thickness in the NbN film, but also to the enlargement of the NbN grains, inherited from the TiN template layer.

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“…Since high T c is preferable for good performance of the HEB mixers, it is important to realize a thin superconducting film with high T c . Furthermore, low resistivity is required in order to maximize an effect of the diffusion cooling used in a supplementary way, in addition to the phonon cooling, because such a 'combination' cooling would be a potential direction for further improvements of the HEB mixer performance [7,8].…”

Section: Introductionmentioning

confidence: 99%

Improvement of the critical temperature of superconducting NbTiN and NbN thin films using the AlN buffer layer

Shiino

Shiba

Sakai

et al. 2010

Supercond. Sci. Technol.

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Thin superconducting NbTiN and NbN films with a few nm thickness are used for various device applications including hot electron bolometer mixers. Such thin films have lower critical temperature (T c) and higher resistivity than corresponding bulk materials. To improve them, we have investigated an effect of the AlN buffer layer between the film and the substrate (quartz or soda lime glass). The AlN film is deposited by DC magnetron sputtering, and the process condition is optimized so as that the X-ray diffraction intensity from the 002 surface of Wurtzite AlN becomes highest. By use of this well-characterized buffer layer, T c and resistivity of the NbTiN film with a few nm thickness are remarkably increased and decreased, respectively, in comparison with those without the buffer layer. More importantly, the AlN buffer layer is found to be effective for NbN. With the AlN buffer layer, T c is increased from 7.3 K to 10.5 K for the 8 nm NbN film. The improvement of T c and resistivity originates Improvement of T c of NbTiN and NbN Thin Films Using the AlN Buffer Layer 2 from the good lattice matching between the 002 surface of AlN and the 111 surface of NbTiN or NbN, which makes better crystallization of the NbTiN or NbN film. This is further confirmed by the X-ray diffraction measurement.

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Development of THz Waveguide NbTiN HEB Mixers

Cited by 15 publications

References 11 publications

High quality NbTiN films fabrication and rapid thermal annealing investigation*

High quality NbTiN films fabrication and rapid thermal annealing investigation*

Improvement of the superconducting properties of NbN thin film on single-crystal silicon substrate by using a TiN buffer layer

Improvement of the critical temperature of superconducting NbTiN and NbN thin films using the AlN buffer layer

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