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Author |
Kroug, M.; Yagoubov, P.; Gol'tsman, G.; Kollberg, E. |
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Title |
NbN quasioptical phonon cooled hot electron bolometric mixers at THz frequencies |
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Conference Article |
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Year |
1997 |
Publication |
Inst. Phys. Conf. Ser. |
Abbreviated Journal |
Inst. Phys. Conf. Ser. |
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Volume |
1 |
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Pages |
405-408 |
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Keywords |
NbN HEB mixers |
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Veldhoven |
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Bristol |
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0951-3248 |
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3rd Eur. Conf. on Applied Superconductivity |
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1600 |
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Author |
Cherednichenko, S.; Yagoubov, P.; Il'In, K.; Gol'tsman, G.; Gershenzon, E. |
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Title |
Large bandwidth of NbN phonon-cooled hot-electron bolometer mixers on sapphire substrates |
Type |
Conference Article |
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Year |
1997 |
Publication |
Proc. 8th Int. Symp. Space Terahertz Technol. |
Abbreviated Journal |
Proc. 8th Int. Symp. Space Terahertz Technol. |
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Pages |
245-257 |
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Keywords |
NbN HEB mixers, fabrication process |
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Abstract |
The bandwidth of NbN phonon-cooled hot electron bolometer mixers has been systematically investigated with respect to the film thickness and film quality variation. The films, 2.5 to 10 mm thick, were fabricated on sapphire substrates using DC reactive magnetron sputtering. All devices consisted of several parallel strips, each 1 1.1 wide and 211 long, placed between Ti-Au contact pads. To measure the gain bandwidth we used two identical BWOs operating in the 120-140 GHz frequency range, one functioning as a local oscillator and the other as a signal source. The majority of the measurements were made at an ambient temperature of 4.5 K with optimal LO and DC bias. The maximum 3 dB bandwidth (about 4 GHz) was achieved for the devices made of films which were 2.5-3.5 nm thick, had a high critical temperature, and high critical current density. A theoretical analysis of bandwidth for these mixers based on the two-temperature model gives a good description of the experimental results if one assumes that the electron temperature is equal to the critical temperature. |
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276 |
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Author |
Kawamura, J.; Blundell, R.; Tong, C-Y. E.; Gol'tsman, G.; Gershenzon, E.; Voronov, B.; Cherednichenko, S. |
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Title |
Phonon-cooled NbN HEB mixers for submillimeter wavelengths |
Type |
Conference Article |
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Year |
1997 |
Publication |
Proc. 8th Int. Symp. Space Terahertz Technol. |
Abbreviated Journal |
Proc. 8th Int. Symp. Space Terahertz Technol. |
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Pages |
23-28 |
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Keywords |
waveguide NbN HEB mixers |
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Abstract |
The noise performance of receivers incorporating NbN phonon-cooled superconducting hot electron bolometric mixers is measured from 200 GHz to 900 GHz. The mixer elements are thin-film (thickness — 4 nm) NbN with —5 to 40 pm area fabricated on crystalline quartz sub- strates. The receiver noise temperature from 200 GHz to 900 GHz demonstrates no unexpected degradation with increasing frequency, being roughly TRx ,; 1-2 K The best receiver noise temperatures are 410 K (DSB) at 430 GHz, 483 K at 636 GHz, and 1150 K at 800 GHz. |
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275 |
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Author |
Ekstörm, H.; Kollberg, E.; Yagoubov, P.; Gol'tsman, G.; Gershenzon, E.; Yngvesson, S. |
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Title |
Gain and noise bandwidth of NbN hot-electron bolometric mixers |
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Journal Article |
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Year |
1997 |
Publication |
Appl. Phys. Lett. |
Abbreviated Journal |
Appl. Phys. Lett. |
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Volume |
70 |
Issue |
24 |
Pages |
3296-3298 |
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Keywords |
NbN HEB mixers, conversion loss, conversion gain, U-factor technique |
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Abstract |
We have measured the noise performance and gain bandwidth of 35 Å thin NbN hot-electron mixers integrated with spiral antennas on silicon substrate lenses at 620 GHz. The best double-sideband receiver noise temperature is less than 1300 K with a 3 dB bandwidth of ≈5 GHz. The gain bandwidth is 3.2 GHz. The mixer output noise dominated by thermal fluctuations is 50 K, and the intrinsic conversion gain is about −12 dB. Without mismatch losses and excluding the loss from the beamsplitter, we expect to achieve a receiver noise temperature of less than 700 K. |
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279 |
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Merkel, H. F.; Yagoubov, P. A.; Kroug, M.; Khosropanah, P.; Kollberg, E. L.; Gol’tsman, G. N.; Gershenzon, E. M. |
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Title |
Noise temperature and absorbed LO power measurement methods for NbN phonon-cooled hot electron bolometric mixers at terahertz frequencies |
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Conference Article |
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Year |
1998 |
Publication |
Proc. 28th European Microwave Conf. |
Abbreviated Journal |
Proc. 28th European Microwave Conf. |
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Volume |
1 |
Issue |
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Pages |
294-299 |
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Keywords |
NbN HEB mixers |
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Abstract |
In this paper the absorbed LO power requirements and the noise performance of NbN based phonon-cooled hot electron bolometric (HEB) quasioptical mixers are investigated for RF frequencies in the 0.55-1.1 range The minimal measured DSB noise temperatures are about 500 K at 640 GHz, 600 K at 750 GHz, 850 K at 910 GHz and 1250 K at 1.1 THz. The increase in noise temperature at 1.1THz is attributed to water absorption. The absorbed LO power is measured using a calorimetric approach. The results are subsequently corrected for lattice heating. These values are compared to results of a novel one dimensional hot spot mixer models and to a more traditional isotherm method which tends to underestimate the absorbed LO power for small bias powers. Typically a LO power between 50nW and 100nW is needed to pump the device to the optimal operating point. |
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28th European Microwave Conference |
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1580 |
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