Development of a waveguide-type hot electron bolometer mixer at 2 THz

We are developing a waveguide-type hot electron bolometer mixer (HEBM) at 2 THz. A membrane-type Ni-NbN HEBM device on a Si3N4 substrate was fabricated in a clean room facility of our laboratory. The membrane bridge with a size of W55 μm x L820 μm x t1 μm was supported by a Si frame with a size of 3 mm by 3 mm and a thickness of 200 μm. The device was installed in a waveguide-type mixer mount with a WR-0.51 waveguide and a diagonal horn. The measured receiver noise temperature and IF gain bandwidth are ~1,690 K in DSB and ~4 GHz which must be improved by getting the HEBM device closer to the design. We are also trying to fabricate a mixer block with a corrugated horn at 2 THz.