Submicron Nb-Al/Al oxide-Nb tunnel junctions sandwiched between Al films

Maier, D.; Rothermel, H.; Gundlach, K. H.; Zimmermann, Ralph

doi:10.1016/0921-4534(96)00398-x

Cited by 10 publications

(6 citation statements)

References 12 publications

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“…To minimize the parasitic capacitance, we define the junction by the overlap of two narrow perpendicular stripes, similar to the work in [19][20][21][22]. As in these references, any unnecessary overlap of the wiring layer with the base electrode is avoided.…”

Section: Fabricationmentioning

confidence: 99%

Sub-micrometer-sized, cross-type Nb–AlOx–Nb tunnel junctions with low parasitic capacitance

Anders

Schmelz

Fritzsch

et al. 2009

Supercond. Sci. Technol.

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We report on a technology for the fabrication of sub-micrometer sized cross-type Josephson tunnel junctions in niobium technology. We present the fabrication scheme and properties of cross-type junctions with linear dimensions from 10 down to 0.6 µm. Sidewall passivation of the junctions is achieved by anodization as well as by planarizing the junctions with SiO in a self-aligned deposition step. The measured ratio of the sub-gap resistance to the normal resistance is about 35. Because of their low sub-gap current and low parasitic capacitance such junctions are well suited for applications like high resolution SQUIDs.

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Section: Fabricationmentioning

confidence: 99%

Sub-micrometer-sized, cross-type Nb–AlOx–Nb tunnel junctions with low parasitic capacitance

Anders

Schmelz

Fritzsch

et al. 2009

Supercond. Sci. Technol.

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“…Efforts have been made to overcome this frequency threshold by replacing the Nb wiring with normal conducting Al films or by introducing NbN with a gap frequency of about 1.2 THz. [1][2][3] However, so far, no break through has been achieved for frequencies above 1 THz.…”

Section: Introductionmentioning

confidence: 96%

Low-noise heterodyne mixing with NbN microbolometers at 800 GHz

Lehnert

Rothermel

Gundlach

1998

Journal of Applied Physics

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Mixer performance of NbN transition edge microbolometers was investigated in a frequency range from 795 to 813 GHz. The devices consist of a parallel array of 3 NbN lines with submicron length patterned by e-beam lithography in a self-aligned process. The heterodyne mixer response was proven by means of two superposed oscillator signals at the receiver input and the observation of a discrete line in the output spectrum. Receiver noise temperatures, Trec, were determined by the hot/cold load Y-factor method in a quasioptical receiver at 4.2 K. The accessible intermediate frequency (IF) band was 1000 to 1750 MHz. We have compared devices with a NbN film thickness of 100 and 50 Å. Lowest receiver noise temperatures were obtained at 800 GHz. Uncorrected Trec values around 900 K were measured for both devices at a 1000 MHz IF frequency. For higher IF frequencies, Trec increased much less in the 50 Å device than in the 100 Å device. At 800 GHz and 1750 MHz IF frequency, Trec was only 1180 K. This result indicates that in an optimized NbN bolometric mixer the IF frequency band can extend to reasonable high values for radioastronomical applications.

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“…Heterodyne mixing experiments with Nb tunnel junctions using Al striplines have been reported by van de Stadt et al [5], Bin et al [6], Maier et al [8] and Schäfer et al [9]. The receiver noise temperatures T REC are summarized in table 1 together with the losses in the striplines G strip .…”

Section: Nb Tunnel Junctions With Al Striplinesmentioning

confidence: 97%

Pushing the operating range of SIS mixers into the THz regime

Klapwijk¹,

Dieleman²,

Graauw³

1997

Supercond. Sci. Technol.

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In recent years, responding to the need of the astronomical community, superconductor - insulator - superconductor (SIS) mixers have been developed to operate at THz frequencies. Best results are obtained by using niobium-based tunnel junctions with well-matched low-loss normal metal striplines, which are found to be less lossy than niobium striplines operated above the gap frequency of niobium (700 GHz). Niobium nitride tunnel junctions with a magnesium oxide tunnel barrier, although having reasonable-quality current - voltage characteristics, have been found to be unsuitable owing to excess shot noise resulting from pinholes in the barrier.

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Submicron Nb-Al/Al oxide-Nb tunnel junctions sandwiched between Al films

Cited by 10 publications

References 12 publications

Sub-micrometer-sized, cross-type Nb–AlOx–Nb tunnel junctions with low parasitic capacitance

Sub-micrometer-sized, cross-type Nb–AlOx–Nb tunnel junctions with low parasitic capacitance

Low-noise heterodyne mixing with NbN microbolometers at 800 GHz

Pushing the operating range of SIS mixers into the THz regime

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