| Records |
| Author |
Lindgren, M.; Currie, M.; Zeng, W.-S.; Sobolewski, R.; Cherednichenko, S.; Voronov, B.; Gol'tsman, G. N. |
| Title |
Picosecond response of a superconducting hot-electron NbN photodetector |
Type |
Journal Article |
| Year |
1998 |
Publication |
Appl. Supercond. |
Abbreviated Journal  |
Appl. Supercond. |
| Volume |
6 |
Issue |
7-9 |
Pages |
423-428 |
| Keywords |
NbN SSPD, SNSPD |
| Abstract |
The ps optical response of ultrathin NbN photodetectors has been studied by electro-optic sampling. The detectors were fabricated by patterning ultrathin (3.5 nm thick) NbN films deposited on sapphire by reactive magnetron sputtering into either a 5×10 μm2 microbridge or 25 1 μm wide, 5 μm long strips connected in parallel. Both structures were placed at the center of a 4 mm long coplanar waveguide covered with Ti/Au. The photoresponse was studied at temperatures ranging from 2.15 K to 10 K, with the samples biased in the resistive (switched) state and illuminated with 100 fs wide laser pulses at 395 nm wavelength. At T=2.15 K, we obtained an approximately 100 ps wide transient, which corresponds to a NbN detector response time of 45 ps. The photoresponse can be attributed to the nonequilibrium electron heating effect, where the incident radiation increases the temperature of the electron subsystem, while the phonons act as the heat sink. The high-speed response of NbN devices makes them an excellent choice for an optoelectronic interface for superconducting digital circuits, as well as mixers for the terahertz regime. The multiple-strip detector showed a linear dependence on input optical power and a responsivity =3.9 V/W. |
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0964-1807 |
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1584 |
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Karasik, B. S.; Il'in, K. S.; Ptitsina, N. G.; Gol'tsman, G. N.; Gershenzon, E. M.; Pechen', E. V.; Krasnosvobodtsev, S. I. |
| Title |
Electron-phonon scattering rate in impure NbC films |
Type |
Abstract |
| Year |
1998 |
Publication |
NASA/ADS |
Abbreviated Journal |
NASA/ADS |
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Issue |
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Pages |
Y35.08 |
| Keywords |
NbC films |
| Abstract |
The study of the electron-phonon interaction in thin (20 nm) NbC films with electron mean free path l=2-13 nm gives an evidence that electron scattering is significantly modified due to the interference between electron-phonon and elastic electron scattering from impurities. The interference ~T^2-term, which is proportional to the residual resistivity, dominates over the Bloch-Grüneisen contribution to resistivity at low temperatures up to 60 K. The electron energy relaxation rate is directly measured via the relaxation of hot electrons heated by modulated electromagnetic radiation. In the temperature range 1.5 – 10 K the relaxation rate shows a weak dependence on the electron mean free path and strong temperature dependence T^n with the exponent n = 2.5-3. This behaviour is well explained by the theory of the electron-phonon-impurity interference taking into account the electron coupling with transverse phonons determined from the resistivity data. |
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American Physical Society, Annual March Meeting, March 16-20, 1998 Los Angeles, CA |
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no |
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Serial |
1591 |
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Il’in, K.S.; Ptitsina, N.G.; Sergeev, A.V.; Gol’tsman, G.N.; Gershenzon, E.M.; Karasik, B.S.; Pechen, E.V.; Krasnosvobodtsev, S.I. |
| Title |
Interrelation of resistivity and inelastic electron-phonon scattering rate in impure NbC films |
Type |
Journal Article |
| Year |
1998 |
Publication |
Phys. Rev. B |
Abbreviated Journal |
Phys. Rev. B |
| Volume |
57 |
Issue |
24 |
Pages |
15623-15628 |
| Keywords |
NbC films |
| Abstract |
A complex study of the electron-phonon interaction in thin NbC films with electron mean free path l=2–13nm gives strong evidence that electron scattering is significantly modified due to the interference between electron-phonon and elastic electron scattering from impurities. The interference T2 term, which is proportional to the residual resistivity, dominates over the Bloch-Grüneisen contribution to resistivity at low temperatures up to 60 K. The electron energy relaxation rate is directly measured via the relaxation of hot electrons heated by modulated electromagnetic radiation. In the temperature range 1.5–10 K the relaxation rate shows a weak dependence on the electron mean free path and strong temperature dependence ∼Tn, with the exponent n=2.5–3. This behavior is explained well by the theory of the electron-phonon-impurity interference taking into account the electron coupling with transverse phonons determined from the resistivity data. |
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0163-1829 |
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1585 |
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Merkel, H. F.; Yagoubov, P. A.; Kroug, M.; Khosropanah, P.; Kollberg, E. L.; Gol’tsman, G. N.; Gershenzon, E. M. |
| Title |
Noise temperature and absorbed LO power measurement methods for NbN phonon-cooled hot electron bolometric mixers at terahertz frequencies |
Type |
Conference Article |
| Year |
1998 |
Publication |
Proc. 28th European Microwave Conf. |
Abbreviated Journal |
Proc. 28th European Microwave Conf. |
| Volume |
1 |
Issue |
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Pages |
294-299 |
| Keywords |
NbN HEB mixers |
| 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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Blundell, R.; Kawamura, J. H.; Tong, C. E.; Papa, D. C.; Hunter, T. R.; Gol’tsman, G. N.; Cherednichenko, S. I.; Voronov, B. M.; Gershenzon, E. M. |
| Title |
A hot-electron bolometer mixer receiver for the 680-830 GHz frequency range |
Type |
Conference Article |
| Year |
1998 |
Publication |
Proc. 6-th Int. Conf. Terahertz Electron. |
Abbreviated Journal |
Proc. 6-th Int. Conf. Terahertz Electron. |
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Issue |
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Pages |
18-20 |
| Keywords |
NbN HEB mixers |
| Abstract |
We describe a heterodyne receiver designed to operate in the partially transparent atmospheric windows centered on 680 and 830 GHz. The receiver incorporates a niobium nitride thin film, cooled to 4.2 K, as the phonon-cooled hot-electron mixer element. The double sideband receiver noise, measured over the frequency range 680-830 GHz, is typically 700-1300 K. The instantaneous output bandwidth of the receiver is 600 MHz. This receiver has recently been used at the SubMillimeter Telescope, jointly operated by the Steward Observatory and the Max Planck Institute for Radioastronomy, for observations of the neutral carbon and CO spectral lines at 810 GHz and at 806 and 691 GHz respectively. Laboratory measurements on a second mixer in the same test receiver have yielded extended high frequency performance to 1 THz. |
| Address |
Leeds, UK |
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IEEE |
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0-7803-4903-2 |
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IEEE Sixth International Conference on Terahertz Electronics Proceedings. THZ 98. (Cat. No.98EX171) |
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1581 |
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