A niobiumnitride mixer with niobium tuning circuit

Plathner, B.; Schicke, M.; Lehnert, Thomas; Gundlach, K. H.; Rothermel, H.; Aoyagi, Masahiro; Takada, S.

doi:10.1063/1.117832

Cited by 6 publications

(5 citation statements)

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“…5 shows the corresponding calculated dV /dI − V dc curves for NbN/Au/2DEG junctions. The parameters for the calculated curves were chosen within a realistic range given by the characteristic material constants [40,41,42,43,44,45]. As can be seen from Fig.…”

Section: Discussion and Comparison With Theorymentioning

confidence: 99%

Andreev reflection and enhanced subgap conductance in NbN∕Au∕InGaAs-InP junctions

Batov

Schaepers

Golubov

et al. 2004

Journal of Applied Physics

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We report on the fabrication of highly transparent superconductor/normal metal/twodimensional electron gas junctions formed by a superconducting NbN electrode, a thin (10nm) Au interlayer, and a two-dimensional electron gas in a InGaAs/InP heterostructure. High junction transparency has been achieved by exploiting of a newly developed process of Au/NbN evaporation and rapid annealing at 400 • C. This allowed us to observe for the first time a decrease in the differential resistance with pronounced double-dip structure within the superconducting energy gap in superconductor-2DEG proximity systems. The effect of a magnetic field perpendicular to the plane of the 2DEG on the differential resistance of the interface was studied. It has been found that the reduced subgap resistance remains in high magnetic fields. Zero-field data are analyzed within the previously established quasiclassical model for the proximity effect.

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Section: Discussion and Comparison With Theorymentioning

confidence: 99%

Andreev reflection and enhanced subgap conductance in NbN∕Au∕InGaAs-InP junctions

Batov

Schaepers

Golubov

et al. 2004

Journal of Applied Physics

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“…Details of the NbN deposition parameters are described elsewhere. 3 The deposition time was adjusted for either a 50 or 100 Å film thickness. The antenna was defined by optical lithography on top of the NbN layer.…”

Section: Device Fabrication and Experimental Setupmentioning

confidence: 99%

“…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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“…DSB receiver noise temperatures around 200 K have been reported at 300 GHz. A receiver with NbN junctions attached to a Nb tuning circuit resulted in a similar noise value: 245 K at 345 GHz (Plathner et al 1996). Receivers using Nb mixers achieve noise temperatures of at least a factor of four lower.…”

Section: Nbn Films and Junctionsmentioning

confidence: 97%

“…The first NbN junctions with Al strip lines were developed in 1997 . The NbN-MgO-NbN junctions were prepared by the room-temperature process mentioned above (Plathner et al 1996). The Al was sputtered or evaporated.…”

Section: Nbn Junctions With Al Embedding Circuitmentioning

confidence: 99%

SIS and bolometer mixers for terahertz frequencies

Gundlach¹,

Schicke²

2000

Supercond. Sci. Technol.

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The need for extremely sensitive heterodyne receivers in the astronomical community has created strong efforts to develop appropriate frequency mixers. Nb/Al-Al x O y -Nb tunnel junctions with Nb matching circuits lead to best results up to approximately 700 GHz, the energy-gap frequency of Nb. For higher frequencies the Nb in the matching circuit becomes lossy and is replaced beyond 800 GHz by Al (which operates in the normal conducting state). The gap frequency of NbN is as high as 1.2 THz, but NbN technology is not yet mature. Practical films still have substantial radio frequency losses and the barrier of NbN tunnel junctions is too leaky. More recently, NbTiN, for which the gap frequency is also about 1.2 THz, was found to have very low losses, and is therefore a good choice for tuning circuits. New interesting tunnel junctions for mixers around 1 THz are NbTiN-MgO-NbTiN and Nb/Al-AlN x -NbTiN. Excellent performance from about 1 THz up to several terahertz can be expected from hot-electron transition-edge bolometer mixers. They consist of NbN or Nb microbridges, they do not need matching circuits and their frequency limit is not determined by the gap frequency.

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A niobiumnitride mixer with niobium tuning circuit

Cited by 6 publications

References 0 publications

Andreev reflection and enhanced subgap conductance in NbN∕Au∕InGaAs-InP junctions

Andreev reflection and enhanced subgap conductance in NbN∕Au∕InGaAs-InP junctions

Low-noise heterodyne mixing with NbN microbolometers at 800 GHz

SIS and bolometer mixers for terahertz frequencies

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