Development of membrane based NbN-HEBs for submillimeter astrophysical applications

We ar e de veloping me mbrane base d Nb N hot electron bolometer ( HEB) arrays for sub-millimet er astrophysical a pplications. He re we rep ort in detail on the device fabr ication process usin g a silicon o xide based resist (HSQ). The e-beam patterned HSQ is used as a mask in reactive ion e tching for HEB de finition a nd the n r emains on top of the HEB pr oviding pr otection against c ontamination. This pr ocess is relative ly s imple s ince it req uires les s s teps th an p reviously reported an d t herefore reduces th e r isk of degradation of th e ultra thin NbN film. To get g ood quality membranes for T Hz- HEB ap plications, d ifferent memb rane p rocess h ave b een investigated. E lectrical ch aracterisations h ave b een p erformed at room an d cryogen ic temp eratures to comp are th e q uality of the de vices with me mbranes made up of Si/SiO 2 or Si 3N4/SiO2 and processed with either dry or wet etching methods.