| 1. |
- Bevilacqua, Stella, 1981, et al.
(författare)
-
Characterisation and Modeling of MgB2 HEBs IF impedance
- 2016
-
Ingår i: Swedish Microwave Days March 15-16, 2016, Linköping, Sweden. ; , s. 55-
-
Konferensbidrag (refereegranskat)abstract
- Here we present the method which allows to measure quiteaccurately the HEB impedance employing just one cooling.By knowing the HEB IF impedance a coupling matchingnetwork can be designed for a possible packaged receiver.
|
|
| 2. |
- Bevilacqua, Stella, 1981, et al.
(författare)
-
Fast room temperature THz bolometers
- 2013
-
Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. - 9781467347174 ; , s. 1-2
-
Konferensbidrag (refereegranskat)abstract
- A responsivity of >100 V/W was measured at roomtemperature for nano scale bolometers integrated with planar spiral antennas covering a frequency range from 100 GHz to 3 THz. Currently a NEP of about 200 pW/Hz^0.5 was experimentally obtained.
|
|
| 3. |
- Bevilacqua, Stella, 1981, et al.
(författare)
-
Fast room temperature THz microbolometers
- 2012
-
Ingår i: 23rd International Symposium on Space Terahertz Technology.
-
Konferensbidrag (refereegranskat)abstract
- We will present experimental and theoretical investigation of room temperature high speed THz detectors based on thin YBa2Cu3O7 films. These films have TCR of 0.35%/K, and can sustain large bias current densities. With a resistivity of 100-200 µOhm×cm for a film thickness of 50nm, it is very straightforward to impedance match such bolometers with planar antennas. The responsivity is a function of the bolometer planar dimensions and the films thickness. The currently achieved responsivity is 30 V/W and Johnson noise limited NEP is 70pW/Hz^0.5. The bolometer bandwidth is limited by the antenna bandwidth and spans from microwaves to over a few THz. Experimenatl investigation is done from 100GHz to 2.5THz. The measured response time is 2ns. We will also present results of the bolometer performance as their dimensions reduce to sub-µm.
|
|
| 4. |
- Bevilacqua, Stella, 1981, et al.
(författare)
-
HEB mixers for THz radio astronomy
- 2014
-
Ingår i: Swedish Microwave Days March 11-12, 2014.
-
Konferensbidrag (refereegranskat)abstract
- Hot-Electron Bolometer (HEB) mixers made of 10 nm superconducting MgB2 films are discussed for high sensitivity high spectral resolution spectrometers for radio astronomy. The key advantage of the used MgB2 films is in achievement of wider Intermediate Frequency (IF) bandwidth.
|
|
| 5. |
- Bevilacqua, Stella, 1981, et al.
(författare)
-
High Sensitivity Terahertz Bolometers as Room Temperature Detectors
- 2014
-
Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. - 9781479938773 ; , s. Art. no. 6956197-
-
Konferensbidrag (refereegranskat)abstract
- High sensitivity room temperature THz direct detectors made of YBa2Cu3O7-x nano-bridges, with a broadband optical coupling (0.1-2THz) are presented. An optical responsivity (RV) up to 45 V/W was measured at 400 GHz. For bolometers with an electrical responsivity of 70 V/W a noise equivalent power (NEP) of 50 pW/Hz0.5 was experimental obtained.
|
|
| 6. |
- Bevilacqua, Stella, 1981, et al.
(författare)
-
Investigation of MgB2 HEB mixer gain bandwidth
- 2011
-
Ingår i: International Conference on Infrared, Millimeter and Terahertz Waves (IRMMW-THz), 2011. - 2162-2027. - 9781457705083 ; , s. 1 - 2
-
Konferensbidrag (refereegranskat)abstract
- THz mixers based on superconducting MgB2 bolometers were fabricated by photolithography and Ar-ion beam milling on sapphire substrates. The mixer gain bandwidth of 3.4 GHz, 2.3 GHz and 1.3 GHz were measured for 10, 15 and 30 nm films respectively.
|
|
| 7. |
- Bevilacqua, Stella, 1981, et al.
(författare)
-
Low noise MgB2 terahertz hot-electron bolometer mixers
- 2012
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 100:3
-
Tidskriftsartikel (refereegranskat)abstract
- We report on low noise terahertz bolometric mixers made of MgB2 superconducting thin films. For a 10-nm-thick MgB2 film, the lowest mixer noise temperature was 600 K at 600 GHz. For 30 to 10-nm-thick films, the mixer gain bandwidth is an inverse function of the film thickness, reaching 3.4 GHz for the 10-nm film. As the critical temperature of the film decreases, the gain bandwidth also decreases, indicating the importance of high quality thin films for large gain bandwidth mixers. The results indicate the prospect of achieving a mixer gain bandwidth as large as 10-8 GHz for 3 to 5-nm-thick MgB2 films.
|
|
| 8. |
- Bevilacqua, Stella, 1981, et al.
(författare)
-
Low Noise Nanometer Scale Room-Temperature YBa2Cu3O7-x Bolometers for THz Direct Detection
- 2014
-
Ingår i: IEEE Transactions on Terahertz Science and Technology. - 2156-342X .- 2156-3446. ; 4:6, s. 653- 660
-
Tidskriftsartikel (refereegranskat)abstract
- We present a detailed investigation of the responsivity and the noise in room temperature THz direct detectors made of YBa2Cu3O7-x (YBCO) thin film nano bolometers. The YBCO nano bolometers are integrated with planar spiral antennas covering a frequency range from 100 GHz to 2 THz. The detectors were characterized at 1.6 THz, 0.7 THz, 400 GHz and 100 GHz. The maximum electrical responsivity of 70 V/W and a minimum noise equivalent power (NEP) of 50 pW/Hz0.5 were measured, whereas the highest optical responsivity was 45 V/W. The 1/f noise in nano bolometers is independent on the device volume and can be found as (VN/V)2=6×10-11×1/f Hz-1 for a given modulation frequency f and a dc voltage V.
|
|
| 9. |
- Bevilacqua, Stella, 1981, et al.
(författare)
-
MgB2 Hot-Electron Bolometer Mixers at Terahertz Frequencies
- 2015
-
Ingår i: IEEE Transactions on Applied Superconductivity. - 1558-2515 .- 1051-8223. ; 25:3, s. 2301104-
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we compare the performance of MgB2 Hot-Electron Bolometer Mixers operating at Local Oscillator frequencies of 0.6 and 1.63 THz. The minimum noise temperatures that were obtained are 700 and 1150 K for 0.6 and 1.63 THz, respectively. The receiver noise bandwidth is of the order of 2.2-3 GHz for 10-nm-thick HEB devices with a Tc of 8.5 K. Sub-micrometer size HEBs were also fabricated with no degradation of the initial film quality when a 20-nm MgB2 film with a Tc of 22 K was used. In the direct detection mode, the maximum voltage responsivity is in the range of 1-2 kV/W at 1.63 THz and the optimal bias current is around 1/4-1/3 of the Ic at 4.2 K.
|
|
| 10. |
- Bevilacqua, Stella, 1981, et al.
(författare)
-
MgB2 Hot Electron Bolometers for THz radio astronomy
- 2012
-
Ingår i: 23rd International Symposium on Space Terahertz Technology.
-
Konferensbidrag (refereegranskat)abstract
- We discuss Hot Electron Bolometer (HEB) THz mixers made of superconducting Magnesium Diboride (MgB2) films. The films of 30 nm, 15 nm and 10 nm thick were deposited on sapphire substrates. The MgB2 HEBs were patterned as a bridge at the feed point of a spiral antenna. The performance of the devices was investigated with respect to the gain bandwidth (GBW) and the noise temperature. The GBW was measured via mixing two signal sources (BWOs at 600 GHz). For the given films thicknesses, the GBW was measured to be 1.3 GHz, 2.3 GHz and 3.4 GHz, which is larger than for the NbN HEB mixers made of the same films thicknesses. Using the Y-factor technique a noise temperature of 800 K at 600 GHz local oscillator (LO) frequency was measured for mixers made of 10 nm MgB2 film. Besides the films thickness, the gain and the noise bandwidths are functions of the films critical temperature, Tc. For 10nm films, with Tc=15K, a noise bandwidth on the order of 8GHz was measured. From these measurements and from the material parameters a GBWof 8 GHz (noise bandwidth >10GHz) is expected for 3-5 nm MgB2 films.
|
|
