Development of a waveguide/membrane 1.5 THz mixer using NbN/AlN/NbN SIS junctions and Al embedding circuits

We report here on the development of a waveguide/membrane NbN-based SIS mixer for use around 1.5 THz. A process has been developed to fabricate the 1-mum(2) NbN/AIn/NbN tunnel junctions on Si wafers and on thin membranes, with Al electrodes. SIMOX 0.6-mum membranes are obtained after processing of a whole 3'' wafer and etching of the individual chips in EDP. A new concept for the mixer block assembly was designed to achieve the critical dimensions of the spacing between the dielectric membrane and the waveguide apertures. A 1.5 THz testbed using a FIR laser is presented that will allow the performance evaluation of this mixer.