The appearance of photon-assisted steps in I-V characteristics of stacked Nb/(Al/AlOx/Nb)n tunnel structures with n=3 and 6 was investigated. The structures were exposed to mm wave irradiation at 45 and 136 GHz. The classical responce of the structures at 45 GHz was observed. At 136 GHz photon-induced steps in the quasiparticle I-V characteristic were observed, which had smaller width than that expected for the corresponding values of frequency and n.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Electrical and Electronic Engineering