ISSTT Proceedings

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Microwave Mixing and IF Bandwidth in Sub-micron Long High-Tc Hot-Electron Bolometers

Authors:
Oliver Harnack, Boris Karasik, William McGrath, Alan Kleinsasser, Jeff Barner
Abstract:
We have systematically measured both the length and temperature dependence of the intermediate frequency (IF) bandwidth of hot-electron bolometer (HEB) mixer made from a high-T superconductor (HTS). Mixer devices with lengths (L) between 50 nm and 1 µm were fabricated from 25 - 35 nm thick YBCO films on YA103 (YAO), MgO, and sapphire substrates. Bandwidth measurements were done using signal and local oscillator (LO) frequencies in the range 1 - 300 GHz. At low operation temperatures where self-heating effects occured, the IF bandwidths were about 30 MHz, 100 MHz, and several 100 MHz for devices on YAO. MgO. and sapphire, respectively. The theoretically predicted L-²-dependence of the IF bandwidths was not observed. At higher operation temperatures. where self-heating disappeared and flux-flow effects define the shape of the IV characteristic (IVC), the measured IF bandwidth increased significantly, while the overall conversion efficiency at low W's decreases by several dB. Our data indicate that the temperature dependence of the HEB mixer performance may be influenced by vortex dynamics effects in HTS materials.
Categories:
High TC, Hot Electron Bolometers
Year:
1999
Session:
4
Full-text:
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Page Number(s):
169-179