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| Author | Bulaevskii, L. N.; Graf, M. J.; Batista, C. D.; Kogan, V. G. | ||||
| Title | Vortex-induced dissipation in narrow current-biased thin-film superconducting strips | Type | Journal Article | ||
| Year | 2011 | Publication | Phys. Rev. B | Abbreviated Journal | Phys. Rev. B |
| Volume | 83 | Issue | 14 | Pages | 9 |
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| Abstract | A vortex crossing a thin-film superconducting strip from one edge to the other, perpendicular to the bias current, is the dominant mechanism of dissipation for films of thickness d on the order of the coherence length ξ and of width w much narrower than the Pearl length Λâ‰<ab>wâ‰<ab>ξ. At high bias currents I*<I<Ic the heat released by the crossing of a single vortex suffices to create a belt-like normal-state region across the strip, resulting in a detectable voltage pulse. Here Ic is the critical current at which the energy barrier vanishes for a single vortex crossing. The belt forms along the vortex path and causes a transition of the entire strip into the normal state. We estimate I* to be roughly Ic/3. Furthermore, we argue that such “hot†vortex crossings are the origin of dark counts in photon detectors, which operate in the regime of metastable superconductivity at currents between I* and Ic. We estimate the rate of vortex crossings and compare it with recent experimental data for dark counts. For currents below I*, that is, in the stable superconducting but resistive regime, we estimate the amplitude and duration of voltage pulses induced by a single vortex crossing. | ||||
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| Notes | SSPD | Approved | no | ||
| Call Number | RPLAB @ gujma @ | Serial | 688 | ||
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| Author | Edlmayr, V.; Harzer, T. P.; Hoffmann, R.; Kiener, D.; Scheu, C.; Mitterer, C. | ||||
| Title | Effects of thermal annealing on the microstructure of sputtered Al2O3 coatings | Type | Journal Article | ||
| Year | 2011 | Publication | J. Vac. Sci. Technol. A | Abbreviated Journal | |
| Volume | 29 | Issue | 4 | Pages | 8 |
| Keywords | Annealing | ||||
| Abstract | The morphology and microstructure of Al2O3 thin films deposited by pulsed direct current magnetron sputtering were studied in the as-grown state and after vacuum annealing at 1000 °C for 12 h using transmission electron microscopy. For the coating deposited under low ion bombardment conditions, the film consists of small γ- and/or δ-Al2O3 grains embedded in an amorphous matrix. The grain size at the region close to the interface to the substrate was much larger than that of the remaining layer. Growth of the γ-Al2O3 phase is promoted during annealing but no transformation to α-Al2O3 was detected. For high-energetic growth conditions, clear evidence for γ-Al2O3 formation was found in the upper part of the coating with grain size much larger than for low-energetic growth, but the film was predominately amorphous at the interface region. Annealing resulted in the transformation of γ-Al2O3 to α-Al2O3, while the mainly amorphous part crystallized to γ-Al2O3. | ||||
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| Notes | Annealing | Approved | no | ||
| Call Number | RPLAB @ gujma @ | Serial | 693 | ||
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| Author | Ozhegov, R. V.; Gorshkov, K. N.; Gol'tsman, G. N.; Kinev, N. V.; Koshelets, V. P. | ||||
| Title | The stability of a terahertz receiver based on a superconducting integrated receiver | Type | Journal Article | ||
| Year | 2011 | Publication | Supercond. Sci. Technol. | Abbreviated Journal | Supercond. Sci. Technol. |
| Volume | 24 | Issue | 3 | Pages | 035003 |
| Keywords | SIS mixer, SIR, stability | ||||
| Abstract | We present the results of stability testing of a terahertz radiometer based on a superconducting receiver with a SIS tunnel junction as the mixer and a flux-flow oscillator as the local oscillator. In the continuum mode, the receiver with a noise temperature of 95 K at 510 GHz measured over the intermediate frequency (IF) passband of 4-8 GHz offered a noise equivalent temperature difference of 10 ± 1 mK at an integration time of 1 s. We offer a method to significantly increase the integration time without the use of complex measurement equipment. The receiver observed a strong signal over a final detection bandwidth of 4 GHz and offered an Allan time of 5 s. | ||||
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| Call Number | RPLAB @ gujma @ | Serial | 705 | ||
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| Author | Флоря, И.Н.; Корнеева, Ю.П.; Корнеев, А.А.; Гольцман, Г.Н. | ||||
| Title | Сверхпроводниковый однофотонный детектор для среднего инфракрасного диапазона на основе узких параллельных полосок | Type | Journal Article | ||
| Year | 2011 | Publication | Труды Московского физико-технического института | Abbreviated Journal | Труды МФТИ |
| Volume | 3 | Issue | 2 | Pages | 14-17 |
| Keywords | SSPD | ||||
| Abstract | Мы рассматриваем ультрабыстрый сверхпроводниковый однофотонный детектор (SSPD). SSPD представляет собой тонкопленочную наноструктуру — очень узкую и длинную полоску сверхпроводника, изогнутую в виде меандра, изготовленную из пленки NbN толщиной 4 нм, нанесенной на сапфировую подложку. SSPD хорошо сопрягается с оптоволокном и легко может быть интегрирован в полностью готовую для работы приемную систему. В стремлении продвинуться в средний ИК диапозон нам удалось разработать SSPD в виде параллельно соединенных полосок с шириной полоски всего 50 нм и сохранить при этом сверхпроводящие свойства. Эти детекторы показывают более чем на порядок большую чувствительность на длине волны 3;5 мкм, чем SSPD в виде меандра. Полученные результаты открывают путь к эффективным детекторам среднего ИК-диапазона, обладающим скоростью счета свыше 1 ГГц. | ||||
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| Call Number | RPLAB @ gujma @ | Serial | 706 | ||
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| Author | Пентин, И. В.; Смирнов, К. В.; Вахтомин, Ю. Б.; Смирнов, А. В.; Ожегов, Р. В.; Дивочий, А. В.; Гольцман, Г. Н. | ||||
| Title | Быстродействующий терагерцевый приемник и инфракрасный счетчик одиночных фотонов на эффекте разогрева электронов в сверхпроводниковых тонкопленочных наноструктурах | Type | Journal Article | ||
| Year | 2011 | Publication | Труды МФТИ | Abbreviated Journal | Труды МФТИ |
| Volume | 3 | Issue | 2 | Pages | 38-42 |
| Keywords | SSPD, SNSPD, HEB | ||||
| Abstract | Представлены результаты создания приемных систем терагерцевого диапазона (0.3-70 ТГц), обладающих рекордным быстродействием (50 пс) и высокой чувствительностью (до 5x 10^(-14) Вт/Гц^(1/2)), а также однофотонных приемных систем ближнего инфракрасного диапазона с квантовой эффективностью 25 %, уровнем темнового счета 10-1c., максимальной скоростью счета ~ 100 МГц и временным разрешением до 50 пс. | ||||
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| Call Number | RPLAB @ gujma @ | Serial | 707 | ||
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| Author | Shangina, E. L.; Smirnov, K. V.; Morozov, D. V.; Kovalyuk, V. V.; Goltsman, G. N.; Verevkin, A. A.; Toropov, A. I.; Mauskopf, P. | ||||
| Title | Concentration dependence of energy relaxation time in AlGaAs/GaAs heterojunctions: direct measurements | Type | Journal Article | ||
| Year | 2011 | Publication | Semicond. Sci. Technol. | Abbreviated Journal | Semicond. Sci. Technol. |
| Volume | 26 | Issue | 2 | Pages | 025013 |
| Keywords | AlGaAs/GaAs heterojunctions | ||||
| Abstract | We present measurements of the energy relaxation time, τε, of electrons in a single heterojunction in a quasi-equilibrium state using microwave time-resolved spectroscopy at 4.2 K. We find the relaxation time has a power-law dependence on the carrier density of the two-dimensional electron gas, τε∝nγs with γ = 0.40 ± 0.02 for values of the carrier density, ns, from 1.6 × 1011 to 6.6 × 1011cm−2. The results are in good agreement with predictions taking into account the scattering of the carriers by both piezoelectric and deformation potential acoustic phonons. We compare these results with indirect measurements of the energy relaxation time from energy loss measurements involving Joule heating of the electron gas. | ||||
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| ISSN | 0268-1242 | ISBN | Medium | ||
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| Notes | Approved | no | |||
| Call Number | Serial | 1215 | |||
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| Author | Расулова, Г.К.; Брунков, П.Н.; Пентин, И.В.; Ковалюк, В.В.; Горшков, К.Н.; Казаков, А.Ю.; Иванов, С.Ю.; Егоров, А.Ю.; Саксеев, Д.А.; Конников, С.Г. | ||||
| Title | Взаимная синхронизация двух связанных генераторов автоколебаний на основе сверхрешеток GaAs/AlGaAs | Type | Journal Article | ||
| Year | 2011 | Publication | Журнал технической физики | Abbreviated Journal | ЖТФ |
| Volume | 81 | Issue | 6 | Pages | 80-86 |
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| Abstract | Проведено исследование взаимодействия генераторов автоколебаний на основе 30-периодной слабосвязанной сверхрешетки GaAs/AlGaAs. Воздействие одного генератора автоколебаний на другой осуществлялось при заданном постоянном смещении в отсутствие в одном из них генерации автономных колебаний. Показано, что вынужденные колебания в захватывающем генераторе возникают из-за возбуждения колебаний в системе связанных осцилляторов, образующих границу электрополевого домена на частоте одной из высших гармоник вынуждающего колебания. | ||||
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| Call Number | RPLAB @ gujma @ | Serial | 711 | ||
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| Author | Mitin, Vladimir; Antipov, Andrei; Sergeev, Andrei; Vagidov, Nizami; Eason, David; Strasser, Gottfried | ||||
| Title | Quantum Dot Infrared Photodetectors: Photoresponse Enhancement Due to Potential Barriers | Type | Journal Article | ||
| Year | 2011 | Publication | Nanoscale Research Letters | Abbreviated Journal | Nanoscale res lett |
| Volume | 6 | Issue | 1 | Pages | 6 |
| Keywords | Quantum dots; Infrared detectors; Photoresponse; Doping; Potential barriers; Capture processes | ||||
| Abstract | Potential barriers around quantum dots (QDs) play a key role in kinetics of photoelectrons. These barriers are always created, when electrons from dopants outside QDs fill the dots. Potential barriers suppress the capture processes of photoelectrons and increase the photoresponse. To directly investigate the effect of potential barriers on photoelectron kinetics, we fabricated several QD structures with different positions of dopants and various levels of doping. The potential barriers as a function of doping and dopant positions have been determined using nextnano3 software. We experimentally investigated the photoresponse to IR radiation as a function of the radiation frequency and voltage bias. We also measured the dark current in these QD structures. Our investigations show that the photoresponse increases ~30 times as the height of potential barriers changes from 30 to 130 meV. | ||||
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| Call Number | RPLAB @ gujma @ | Serial | 712 | ||
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| Author | Семенов, А. В.; Девятов, И. А.; Рябчун, С. А.; Масленников, С. Н.; Масленникова, А. С.; Ларионов, П. А.; Воронов, Б. М.; Чулкова, Г. М. | ||||
| Title | Поглощение терагерцового электромагнитного излучения в “грязной” сверхпроводниковой пленке при произвольном виде спектральных функций | Type | Journal Article | ||
| Year | 2011 | Publication | Ж. Радиоэлектрон. | Abbreviated Journal | |
| Volume | 10 | Issue | Pages | 7 | |
| Keywords | terahertz electromagnetic radiation; superconductors; detectors of terahertz range | ||||
| Abstract | A problem of absorption of high-frequency electromagnetic field in dirty superconductor is treated within Keldysh technic. Expression for the source term in the kinetic equation for quasiparticle distribution function is derived. The result is significant for deriving a consistent microscopic theory of superconducting detectors for terahertz frequency range, perspective detectors on kinetic inductance of current-biased superconducting strip and on Josephson inductance of tunnel. В технике Келдыша рассмотрена задача о поглощении мощности высокочастотного электромагнитного поля в сверхпроводнике, удовлетворяющем условию грязного предела. Получено выражение для члена источника в кинетическом уравнении для функции распределения квазичастиц, справедливое при произвольном виде спектральных функций. Этот результат имеет значение для развития последовательной микроскопической теории сверхпроводниковых детекторов излучения терагерцового диапазона, в частности, перспективных детекторов на кинетической индуктивности смещённой током сверхпроводниковой полоски и джозефсоновской индуктивности туннельного контакта. |
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| Notes | Duplicated as 1117 | Approved | no | ||
| Call Number | RPLAB @ gujma @ | Serial | 713 | ||
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| Author | Семенов, А. В.; Девятов, И. А.; Третьяков, И. В.; Лобанов, Ю. В.; Ожегов, Р. В.; Петренко, Д. В.; Селиверстов, С. В.; Финкель, М. И. | ||||
| Title | Вывод уравнения типа уравнения гинзбурга-ландау для нанопроволоки вблизи критического магнитного поля | Type | Journal Article | ||
| Year | 2011 | Publication | Журнал радиоэлектроники | Abbreviated Journal | Ж. радиоэлектроники |
| Volume | 11 | Issue | Pages | 4 | |
| Keywords | superconductivity; nanowire; Ginzburg-Landau equation | ||||
| Abstract | Nonlinear Ginzburg-Landau equation for dirty supercondicting 1D wire is derived in the limit of high magnetic field. В пределе больших магнитных полей выведено нелинейное уравнение Гинзбурга-Ландау, описывающее состояние одномерной «грязной» нанопроволоки. |
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| Call Number | RPLAB @ gujma @ | Serial | 714 | ||
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