HTS mixers based on the Josephson effect and on the hot-electron bolometric effect

We report on our experimental studies of high-T-C Josephson mixers and high -T-C hot-electron bolometric (HEB) effect mixers. Mixers based on high-T-C bicrystal Josephson junctions have been fabricated, and noise, conversion e fficiency, and receiver bandwidth measurements have been performed in the f requency range between 90 and 550 GHz. The dependence of the mixer performa nce on the operation temperature has been studied. High-T-C HEB mixers have been fabricated on MgO and sapphire substrates. We successfully sized the dimensions of the effective device volume down and managed to fabricate 50- 60 nm long devices. In such short structures phonon diffusion into the norm al metal electrodes should significantly improve the mixer performance.