Computer Science – Performance
Scientific paper
Jan 2007
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2007phdt.......249h&link_type=abstract
Doctoral thesis, Technical University of Delft, The Netherlands, January 2007, 160 pages
Computer Science
Performance
Scientific paper
Prior to our research various groups have successfully demonstrated NbN HEB detectors. However, these pioneering results were not reproducible, as were our own initial results. We have since experimentally found that the contact to the NbN film is the relevant parameter to this issue. Since the contact influences both the device performance and reproducibility we have conducted several experiments to study the effects of the contacts (Chapter 3). This resulted in new contact structures that drastically improved the reproducibility but also yielded a record sensitivity (Chapter 4). Additionally, the improved reproducibility enabled a systematic study of three key parameters for the device physics: firstly, the resistive transition as a function of temperature and current, secondly the behavior of the current as a function of DC voltage and applied local oscillator power, and thirdly the IF bandwidth, thereby advancing the understanding of the device physics (Chapter 2). However, the focus of this work remained performance/application driven. To realize a usable heterodyne receiver the HEB's LO power requirement needed to be reduced, while at the same time the sensitivity should be preserved. This was realized successfully by a reduction of the device-area by about a factor of ten. We performed a full characterization of a receiver based on such a small volume HEB and a solid state LO source showing its usability up to about 2 THz (Chapter 5). Space qualification tests were performed on HEB's leading to the observation of deterioration over time when exposed to normal atmospheric conditions. This was successfully solved by the introduction of a capping layer to protect the ultra-thin NbN film (Chapter 8). As a spin-off of similar qualification tests we found that annealing can increase the sensitivity of HEB's (Chapter 6). The ultimate demonstration of an actual heterodyne receiver for the range between 2 - 6 THz was greatly helped by quantum cascade lasers (QCL) becoming available. Using the QCL as a LO source we successfully characterized a fully operational heterodyne receiver based on a HEB (Chapter 7).
No associations
LandOfFree
Terahertz heterodyne mixing with a hot electron bolometer and a quantum cascade laser does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Terahertz heterodyne mixing with a hot electron bolometer and a quantum cascade laser, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Terahertz heterodyne mixing with a hot electron bolometer and a quantum cascade laser will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1250596