Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Japanese Journal of Applied Physics

Nb-Pb-Nb Planar Josephson Junction Fabricated by RIE

Shigeru Yoshimori, Mitsuo Kawamura

Published Jul 1, 1986• 8 citations
Publisher

Abstract

Nb-Pb-Nb planar Josephson junctions were fabricated by electron-beam exposure and Reactive-Ion-Etching (RIE) and their response characteristics under millimeter-and submillimeter-wave radiation were investigated. The size of the weak-link was 0.67-1.0 micrometers long, 5.0 micrometers wide and 1000Å thick. The fourth Shapiro step under 70 GHz millimeter-wave radiation could be observed. On the other hand, the planar junctions showed only a bolometric response under 891 GHz submillimeter-wave radiation. In this paper, the characteristics of RIE using a CBrF3 gas as the etchant and an electron beam resist, PMMA, as the mask material are also discussed.

DOI
10.1143/jjap.25.1011

Related papers

Fabrication of Niobium Nanobridge Josephson Junctions

Takashi Tachiki, Kenji Horiguchi, Takashi Uchida

To realize antenna-coupled Josephson detectors for microwave and millimeter-wave radiation, planar-type Nb nanobridge Josephson junctions were fabricated. Nb thin films whose thickness, the root mean square roughness and the critical temperature were 20.0 nm, 0.109 nm and 8.4 K, respectively were deposited using a DC magnetron sputtering at a substrate temperature of 700°C. Nanobridges were obtained from the film using 80-kV electron beam lithography and reactive ion-beam etching in CF 4 (90%) + O2 (10%) gases. The minimum bridge area was 65 nm wide and 60 nm long. For the nanobridge whose width and length were less than 110 nm, an I-V characteristic showed resistively-shunted-junction behaviour near the critical temperature. Moreover, Shapiro steps were observed in the nanobridge with microwave irradiation at a frequency of 6 – 30 GHz. The Nb nanobridges can be used as detectors in the antenna-coupled devices.

Journal of Physics Conference Series•May 12, 2014•1 citation

Millimeter and submillimeter wave responses of YBa/sub 2/Cu/sub 3/O/sub 7/ step-edge Josephson junctions

Hisashi Shimakage, Yoshinori Uzawa, Z. Wang +3 more

We have fabricated YBCO step-edge Josephson junctions and measured the responses to millimeter and submillimeter irradiation. In the substrate milling process for the purpose of fabricating the step, the step angle was controlled using a Nb metal mask. At a step angle of 20 degrees, we obtained Josephson junctions, the characteristics of which are consistent with the RSJ model. We estimated the capacitance to be 4.4 fF using the RSJ model, but such a value for an 8 /spl mu/m wide and 300 nm thick junction seems too small. When the junctions were irradiated by 300 GHz radiation, Shapiro steps up to the 4th were observed. The junctions were used as mixers in the 100 GHz band, and as harmonic mixers in the 100 GHz LO and 700 GHz RF bands. Beat signals were observed in both cases. We also estimated the quasi-optical conversion losses of the step-edge junctions as mixers.>

IEEE Transactions on Applied Superconductivity•Jun 1, 1995•13 citations

Millimeter and submillimeter wave responses of YBa2Cu307 step-edge Josephson junctions

Hisashi Shimakage, Yoshinori Uzawa, Z. Wang +3 more

We have fabricated YBCO step-edge Josephson junctions and measured the responses to the millimeter and submillimeter irradiation. In the substrate milling process for the purpose of fabricat- ing the step, the step angle was controlled using a Nb metal mask. At a step angle of 20 degrees, we obtained Josephson junctions, the characteristics of which are consistent with the RSJ model. We estimated the ca- pacitance to be 4.4 fF using the RSJ model, but such a value for an 8 pm wide and 300 nm thick junction seems too small. When the junctions were irradiated by 300 GHz, Shapiro steps up to the 4th were ob- served. The junctions were used as mixers in the 100 GHz band, and as harmonic mixers in the 100 GHz LO and 700 GHz RF bands. Beat signals were observed in both cases. We also estimated the quasi-optical con- version losses of the stepedge junctions as mixers.

•Jan 1, 1995•0 citations

High T/sub c/ superconducting step-edge junctions and their properties in millimeter-wave band

Yijun Feng, L. Kang, X. B. Wang +8 more

Superconducting step-edge junctions were fabricated on step-edges in (100) LaAlO/sub 3/ substrates by sputter-deposited epitaxial YBaCuO and TlBaCaCuO thin films. The substrate steps were patterned by ion beam etching using metal film as a mask. The transport properties of the junctions were characterized by four-probe electrical measurements. The critical current-normal resistance product (I/sub c/R/sub N/) was larger than 0.2 mV (77 K) for most of the junctions. Clear Shapiro steps were observed in the current-voltage characteristics of the junctions with 36 GHz or 95 GHz millimeter-wave irradiation. The high frequency properties of these high T/sub c/ Josephson junctions showed that they were quite suitable for the Josephson harmonic mixer used in the digital phase locked millimeter and sub-millimeter wave sources.>

IEEE Transactions on Applied Superconductivity•Jun 1, 1995•1 citation

All-NbN nanobridges as Josephson mixers

Toshiaki Matsui, Z. Wang, K. Hamasaki +2 more

Using RIE (reactive in etching) and lift-off techniques, all-NbN nanobridges with gap structure in the I-V (current-voltage) curves have been reproducibly constructed for testing as millimeter-wave mixers. The nanobridges were constructed on NbN/MgO/NbN edge junctions. They were characterized by measurements of their I-V curve and dI/dV versus V and by mixing experiments at 105.9 GHz. These devices had high normal-state resistance, and showed almost ideal Josephson response to external magnetic flux and to millimeter-wave irradiation. The I-V curve remained nonhysteretic from T/sub c/ to 4.2 K, and millimeter-wave-induced steps in the I-V curve were observed up to approximately 3 mV. The cooling of the NbN nanobridges was quite good due to their small size and VTB geometry and the high thermal conductivity of the MgO films. Hence the Josephson response of these devices to millimeter waves was comparatively less limited by self-heating.>

IEEE Transactions on Magnetics•Mar 1, 1989•5 citations

Submillimeter-Wave Response of Nb-YBaCuO Point-Contact Josephson Junctions

Syozo Imai, Tadayuki Tozawa, Gin-ichiro Oya +3 more

Shapiro steps in the submillimeter-wave (SMMW) range were observed in junctions made of a high-T c superconductor, YBa2Cu3O x (YBaCuO), and niobium. Junctions were made by pressing a Nb needle on a sintered YBaCuO disk. Shapiro steps up to the fifth order were observed for SMMWs of wavelength 871.6 µm (frequency 344.0 GHz). The dependence of the Shapiro step width on the SMMW power is in accordance with the Bessel function dependence. For SMMWs of wavelength 570.6 µm (525.4 GHz), Shapiro steps up to the second order were observed.

Japanese Journal of Applied Physics•Apr 1, 1988•6 citations
Nb-Pb-Nb planar Josephson junctions were fabricated by electron-beam exposure and Reactive-Ion-Etching (RIE) and their response characteristics under millimeter-and submillimeter-wave radiation were investigated. The size of the weak-link was 0.67-1.0 micrometers long, 5.0 micrometers wide and 1000Å thick. The fourth Shapiro step under 70 GHz millimeter-wave radiation could be observed. On the other hand, the planar junctions showed only a bolometric response under 891 GHz submillimeter-wave radiation. In this paper, the characteristics of RIE using a CBrF3 gas as the etchant and an electron beam resist, PMMA, as the mask material are also discussed.
To realize antenna-coupled Josephson detectors for microwave and millimeter-wave radiation, planar-type Nb nanobridge Josephson junctions were fabricated. Nb thin films whose thickness, the root mean square roughness and the critical temperature were 20.0 nm, 0.109 nm and 8.4 K, respectively were deposited using a DC magnetron sputtering at a substrate temperature of 700°C. Nanobridges were obtained from the film using 80-kV electron beam lithography and reactive ion-beam etching in CF 4 (90%) + O2 (10%) gases. The minimum bridge area was 65 nm wide and 60 nm long. For the nanobridge whose width and length were less than 110 nm, an I-V characteristic showed resistively-shunted-junction behaviour near the critical temperature. Moreover, Shapiro steps were observed in the nanobridge with microwave irradiation at a frequency of 6 – 30 GHz. The Nb nanobridges can be used as detectors in the antenna-coupled devices.
We have fabricated YBCO step-edge Josephson junctions and measured the responses to millimeter and submillimeter irradiation. In the substrate milling process for the purpose of fabricating the step, the step angle was controlled using a Nb metal mask. At a step angle of 20 degrees, we obtained Josephson junctions, the characteristics of which are consistent with the RSJ model. We estimated the capacitance to be 4.4 fF using the RSJ model, but such a value for an 8 /spl mu/m wide and 300 nm thick junction seems too small. When the junctions were irradiated by 300 GHz radiation, Shapiro steps up to the 4th were observed. The junctions were used as mixers in the 100 GHz band, and as harmonic mixers in the 100 GHz LO and 700 GHz RF bands. Beat signals were observed in both cases. We also estimated the quasi-optical conversion losses of the step-edge junctions as mixers.>
We have fabricated YBCO step-edge Josephson junctions and measured the responses to the millimeter and submillimeter irradiation. In the substrate milling process for the purpose of fabricat- ing the step, the step angle was controlled using a Nb metal mask. At a step angle of 20 degrees, we obtained Josephson junctions, the characteristics of which are consistent with the RSJ model. We estimated the ca- pacitance to be 4.4 fF using the RSJ model, but such a value for an 8 pm wide and 300 nm thick junction seems too small. When the junctions were irradiated by 300 GHz, Shapiro steps up to the 4th were ob- served. The junctions were used as mixers in the 100 GHz band, and as harmonic mixers in the 100 GHz LO and 700 GHz RF bands. Beat signals were observed in both cases. We also estimated the quasi-optical con- version losses of the stepedge junctions as mixers.
Superconducting step-edge junctions were fabricated on step-edges in (100) LaAlO/sub 3/ substrates by sputter-deposited epitaxial YBaCuO and TlBaCaCuO thin films. The substrate steps were patterned by ion beam etching using metal film as a mask. The transport properties of the junctions were characterized by four-probe electrical measurements. The critical current-normal resistance product (I/sub c/R/sub N/) was larger than 0.2 mV (77 K) for most of the junctions. Clear Shapiro steps were observed in the current-voltage characteristics of the junctions with 36 GHz or 95 GHz millimeter-wave irradiation. The high frequency properties of these high T/sub c/ Josephson junctions showed that they were quite suitable for the Josephson harmonic mixer used in the digital phase locked millimeter and sub-millimeter wave sources.>
Using RIE (reactive in etching) and lift-off techniques, all-NbN nanobridges with gap structure in the I-V (current-voltage) curves have been reproducibly constructed for testing as millimeter-wave mixers. The nanobridges were constructed on NbN/MgO/NbN edge junctions. They were characterized by measurements of their I-V curve and dI/dV versus V and by mixing experiments at 105.9 GHz. These devices had high normal-state resistance, and showed almost ideal Josephson response to external magnetic flux and to millimeter-wave irradiation. The I-V curve remained nonhysteretic from T/sub c/ to 4.2 K, and millimeter-wave-induced steps in the I-V curve were observed up to approximately 3 mV. The cooling of the NbN nanobridges was quite good due to their small size and VTB geometry and the high thermal conductivity of the MgO films. Hence the Josephson response of these devices to millimeter waves was comparatively less limited by self-heating.>
Shapiro steps in the submillimeter-wave (SMMW) range were observed in junctions made of a high-T c superconductor, YBa2Cu3O x (YBaCuO), and niobium. Junctions were made by pressing a Nb needle on a sintered YBaCuO disk. Shapiro steps up to the fifth order were observed for SMMWs of wavelength 871.6 µm (frequency 344.0 GHz). The dependence of the Shapiro step width on the SMMW power is in accordance with the Bessel function dependence. For SMMWs of wavelength 570.6 µm (525.4 GHz), Shapiro steps up to the second order were observed.