High- T _c superconducting THz emitters fabricated by wet etching

We studied the etching of small crystals of the high-T_c superconductor Bi₂Sr₂CaCu₂O_8+δ (Bi2212) with various dilute compositions of hydrochloric and nitric acids. A particular mixture of those acids was chosen to simultaneously fabricate multiple rectangular stand-alone Bi2212 mesa structures from a large, doubly-cleaved and doubly metallic-coated single crystal. The radiation characteristics of these devices were found to be very similar to stand-alone devices fabricated previously using dry-etching techniques. The greatly reduced time and cost of fabrication of stand-alone Bi2212 devices using our wet-etching technique should facilitate the mass production of a large number of identical stand-alone devices from a large single-crystalline Bi2212 substrate.