Title :
IF bandwidth and noise temperature measurements of NbN HEB mixers on MgO substrates
Author :
Miki, Shigehito ; Uzawa, Yoshinori ; Kawakami, Akira ; Wang, Zhen
Author_Institution :
Graduate Sch. of Sci. & Technol., Kobe Univ., Japan
fDate :
3/1/2001 12:00:00 AM
Abstract :
We report the fabrication and testing of hot electron bolometric mixers with an ultrathin NbN film as heterodyne receivers operating at terahertz frequencies. We found that the quality of the NbN strip is usually degraded by damage resulting from the fabrication process, and we developed a process for reducing such damage. We also fabricated HEB mixers with a new structure in order to study the IF bandwidth determined by the original quality of the NbN thin films. Investigations at 100 GHz revealed that the widest IF bandwidth of 2.0 GHz was obtained by a mixer based on a 2.8 nm-thick NbN film. An HEB mixer based on the 2.8 nm-thick NbN film was also fabricated and evaluated. The receiver noise temperature at 900 GHz was 780 K, the absorbed LO power was about 400 nW, and the conversion gain was -13 dB
Keywords :
bolometers; hot carriers; niobium compounds; sputter deposition; submillimetre wave mixers; submillimetre wave receivers; superconducting device noise; superconducting device testing; superconducting microwave devices; superconducting mixers; superconducting thin films; -13 dB; 100 GHz; 2 GHz; 2.8 nm; 400 nW; 900 GHz; HEB mixer; IF bandwidth; MgO; MgO substrates; NbN; NbN hot electron bolometric mixers; NbN strip; absorbed LO power; conversion gain; fabrication process; heterodyne receivers; noise temperature measurements; receiver noise temperature; terahertz frequencies; testing; ultrathin NbN film; Bandwidth; Degradation; Electrons; Fabrication; Frequency; Gain; Strips; Temperature measurement; Testing; Transistors;
Journal_Title :
Applied Superconductivity, IEEE Transactions on