2.5 THZ NBN HOT-ELECTRON MIXER WITH INTEGRATED TAPERED SLOT ANTENNA

A Hot Electron Bolometer (HEB) mixer for 2.5 THz utilizing a NbN thin film device, integrated with a Broken Linearly Tapered Slot Antenna (B LTSA), has been fabricated and is presently being tested. The NbN HEB device and the antenna were fabricated on a SiO2 membrane. A 0.5 micro meter thick SiO2 layer was grown by rf magnetron reactive sputtering o n a GaAs wafer. The HEB device (phonon-cooled type) was produced as se veral parallel strips, 1 micrometer wide, from ultrathin NbN film 4-7 nm thick, that was deposited onto the SiO2 layer by dc magnetron react ive sputtering. The BLTSA was photoetched in a multilayer Ti-Au metall ization. In order to strengthen the membrane, the front-side of the wa fer was coated with a 5 micrometer thick polyimide layer just before t he membrane formation. The last operation was anisotropic etching of t he GaAs in mixture of HNO3 and H2O2.