Hydrochloric acid modification process for fabricating Bi sub(2)Sr sub(2)CaCu sub( 2)O sub(8+x) THz oscillator stack on-chip coupled to THz detector

We fabricated Bi sub(2)Sr sub(2)CaCu sub( 2)O sub(8+ delta ) (Bi-2212) intrinsic Josephson junctions (IJJ) integrating of an oscillator and a detector by double side photolithography and material modification with a dilutehydrochloric acid solution (pH = 1.65) within a monolithic Bi-2212 crystal. The dilute hydrochloric solution modifies Bi-2212 to insulating BiOCl. Various lateral dimensions of the oscillator IJJ from 45 x 8 to 95 x 30 mu m super(2) were formed; all of the detectors were about 15 x 10 to 15 x 30 mu m super(2) in lateral dimensions. These stacks have 180-416 junctions. Zero voltage current for the detector stack was measured at 77K while sweeping a bias voltage in the oscillator stack. The zero voltage current of the detector stack was strongly suppressed when a kink structure in the current-voltage curve of the oscillator stacks appeared. This indicates that the oscillator stack emits radiation at this voltage. From the Josephson voltage-frequency relation, it is found that the voltage corresponds to about 0.5-1 THz.