High critical current density NbN/AlN/NbN tunnel junctions fabricated on ambient temperature MgO substrates

Wang, Zhen; Kawakami, Akira; Uzawa, Yoshinori; Komiyama, Bokuji

doi:10.1063/1.111730

Cited by 63 publications

(30 citation statements)

References 14 publications

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“…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.…”

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confidence: 55%

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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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confidence: 55%

“…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%

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

et al. 2016

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“…NbN films can be epitaxially grown on MgO (100) single crystal substrates or MgO-buffered semiconductor wafers. 24,25 The crystal structure of NbN/Ni 60 Cu 40 /NbN trilayers were investigated by XRD. Figure 1 Fig.…”

confidence: 99%

Ferromagnetic Josephson junctions based on epitaxial NbN/Ni60Cu40/NbN trilayer

Zhang

et al. 2018

AIP Advances

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We fabricated and characterized a weakly coupled magnetic Josephson junction based on epitaxial NbN/Ni60Cu40/NbN trilayer heterostructures on single crystal MgO (100) substrates. X-ray diffraction and cross-sectional scanning transmission electron microscopy were used to verify the epitaxial growth of NbN/Ni60Cu40/NbN trilayer, while the ferromagnetic properties of NiCu on NbN film were recorded by plotting the magnetization as a function of both the temperature and the magnetic field strength. The NbN/Ni60Cu40/NbN junctions demonstrated typical Josephson effect with a nonlinear overdamped current–voltage characteristic and a characteristic voltage of 9.1 μV. The magnetic field dependence of the junction critical current showed a nearly ideal Fraunhofer-like pattern with a magnetic field shift of about 12 Oe due to the remanent magnetization of Ni60Cu40 layer.

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“…We have previously developed NbN tunnel junctions with epitaxially grown NbN films 14 and an aluminum nitride (AlN) barrier deposited by rf reactive sputtering on singlecrystal MgO (100) substrates. 15,16 Since both NbN and AlN have nitrogen in common, it is expected that clean electrodebarrier interfaces can be formed in NbN/AlN/NbN tunnel junctions with improved junction quality. In the previous work, however, we found that the crystal structures of the counter electrode NbN films were dependent on the thickness of the AlN barriers, resulting in different junction qualities depending on J c .…”

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confidence: 99%