High-quality epitaxial NbN/AlN/NbN tunnel junctions with a wide range of current density

Wang, Z.; Terai, Hirotaka; Qiu, Wei; Makise, Kazumasa; Uzawa, Yoshinori; Kimoto, Koji; Nakamura, Y.

doi:10.1063/1.4801972

Cited by 50 publications

(41 citation statements)

References 31 publications

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“…The barrier height is about the same value as the epitaxial NbN/AlN/NbN tunnel junctions fabricated on single crystal MgO substrates (0.9 eV), 8 suggesting epitaxial growth of NbN/AlN/NbN trilayers on Si substrates with TiN buffer layers.…”

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confidence: 53%

“…For all junctions, the junction quality is similar to that of the epitaxial NbN/AlN/NbN junctions fabricated on single-crystal MgO substrates. [6][7][8] These results suggest that our NbN/AlN/NbN junctions fabricated on the Si substrate with the TiN buffer layer are also epitaxial junctions. Figure 3 shows the current density J c values of the junctions with different thicknesses of the AlN barriers.…”

mentioning

confidence: 52%

“…1-5 Epitaxial NbN/AlN/NbN junctions fabricated on single-crystal MgO substrates have excellent junction quality, [6][7][8] and demonstrate good performance as superconducting electronics devices. [9][10][11][12] In most superconducting electronics applications, the junctions must be prepared on various substrates.…”

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confidence: 99%

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Epitaxial NbN/AlN/NbN tunnel junctions on Si substrates with TiN buffer layers

et al. 2016

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We have developed epitaxial NbN/AlN/NbN tunnel junctions on Si (100) substrates with a TiN buffer layer. A 50-nm-thick (200)-oriented TiN thin film was introduced as the buffer layer for epitaxial growth of NbN/AlN/NbN trilayers on Si substrates. The fabricated NbN/AlN/NbN junctions demonstrated excellent tunneling properties with a high gap voltage of 5.5 mV, a large IcRN product of 3.8 mV, a sharp quasiparticle current rise with a ΔVg of 0.4 mV, and a small subgap leakage current. The junction quality factor Rsg/RN was about 23 for the junction with a Jc of 47 A/cm2 and was about 6 for the junction with a Jc of 3.0 kA/cm2. X-ray diffraction and transmission electron microscopy observations showed that the NbN/AlN/NbN trilayers were grown epitaxially on the (200)-orientated TiN buffer layer and had a highly crystalline structure with the (200) orientation.

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Epitaxial NbN/AlN/NbN tunnel junctions on Si substrates with TiN buffer layers

et al. 2016

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“…During that time, the quality of junctions was not good, i.e., with a gap voltage V g less than 5 mV and a high leakage current, so the NbN SQUIDs showed a high 1/f noise in the range of 100 Hz. For many years, NbN/AlN/NbN junctions have attracted interest in applications of superconducting electronics, because NbN/AlN/NbN junctions exhibit high qualities with a large gap voltage of 5.6 mV, a large quality factor R sg /R n and a large subgap leakage factor V m [11]. Recently, we have developed high quality epitaxial NbN/AlN/NbN Josephson tunnel junctions in Shanghai Institute of Microsystem and Information Technology.…”

Section: Introductionmentioning

confidence: 99%

All-NbN DC-SQUID Magnetometer Based on NbN/AlN/NbN Josephson Junctions

Liu

Wang

Zhang

et al. 2017

IEEE Trans. Appl. Supercond.

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We have developed an all-NbN-integrated dc SQUID magnetometer for future applications in the higher operating temperature by taking advantage of NbN films' higher critical temperature about 16 K. Our NbN dc SQUID magnetometer is fabricated on a single crystal MgO (100) substrate, consisting of epitaxial NbN/AlN/NbN Josephson junctions, Ti/Pd shunt resistors, and a top 400-nm-thick NbN wiring layer. The critical current, inductance, and shunt resistance of NbN SQUID are set at 20 μA, 240 pH, and 1 Ω, respectively. We measured the current-voltage characteristics, voltage-flux characteristics and flux noise of the NbN SQUID magnetometer in a superconductive niobium shield at 4.2 K. In a flux locked loop operation mode, the NbN SQUID magnetometer exhibits excellent performances with a flux noise level of 6 μΦ 0 /ÝHz in the white region. The corner frequency is only 10 Hz. Based on the calibrated magnetic field sensitivity of 1.7 nT/Φ 0 at magnetically shielded room, the magnetic field resolution of 10 fT/ÝHz is achieved.

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“…Bin a Nb SIS mixer using a double normal-conducting embedding structure made of Al, however, they obtained a higher receiver noise temperature of approximately 840 K at 1042 GHz due to the rf -signal loss in the Al. Recently, Wang et al 15 fabricated high-quality, high-current density niobium nitride (NbN) SIS junctions with aluminumnitride tunnel barriers where the complete embedding circuit also consists of the high-gap superconductor NbN.…”

Section: Introductionmentioning

confidence: 99%

Improved Nb SIS devices for heterodyne mixers between 700 GHz and 1.3 THz with NbTiN transmission lines using a normal metal energy relaxation layer

Westig

Selig

Jacobs

et al. 2013

Journal of Applied Physics

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In this paper we demonstrate experimentally the implementation of a niobium-trilayer junction with an aluminum-oxide tunnel barrier, embedded in a high-gap superconducting niobium-titanium-nitride circuit. Previously reported heating by quasiparticle trapping is removed by inserting a normal metal layer of gold between the niobium junction and the niobium-titanium-nitride layer. We analyze in dc-characterization measurements the cooling of the nonequilibrium quasiparticles in various device geometries having different gold layer thickness and shape. Our work is concluded with remarks for future heterodyne mixer experiments using our device technology.

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High-quality epitaxial NbN/AlN/NbN tunnel junctions with a wide range of current density

Abstract: Articles you may be interested inBias current ramp rate dependence of the crossover temperature from Kramers to phase diffusion switching in moderately damped NbN/AlN/NbN Josephson junctions

Cited by 50 publications

References 31 publications

Epitaxial NbN/AlN/NbN tunnel junctions on Si substrates with TiN buffer layers

Epitaxial NbN/AlN/NbN tunnel junctions on Si substrates with TiN buffer layers

All-NbN DC-SQUID Magnetometer Based on NbN/AlN/NbN Josephson Junctions

Improved Nb SIS devices for heterodyne mixers between 700 GHz and 1.3 THz with NbTiN transmission lines using a normal metal energy relaxation layer

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