Design and characterization of single crystalline Bi-2223 mesas towards the observation of coherent terahertz radiation emitted from trilayer intrinsic Josephson junctions*

Coherent and continuous terahertz electromagnetic radiation emitted from stacks of intrinsic Josephson junctions (IJJs) has been observed solely from a bilayer Bi-2212 system [L. Ozyuzer et al., Science vol. 318, p. 1291 (2007)]. In this study, we focus on a trilayer Bi-2223 system, which consists of triple superconducting copper oxide layers per unite cell. Since an optimally doped Bi-2223 crystal exhibits the superconducting critical temperature above 100 K, we can expect to obtain appreciable emissions at remarkably high operation temperatures. Here, we fabricate Bi-2223 rectangular mesas in a conventional manner using photolithography and argon ion milling techniques. Unfortunately, we have not yet succeeded in observing intense emission from Bi-2223 mesas. Nevertheless, there are indications that the trilayer Bi-2223 system differs essentially from the bilayer Bi-2212 system in terms of the c-axis interlayer coupling. In the poster, we will discuss the multiple quasiparticle branches seen in the current-voltage characteristics of the Bi-2223 mesas. We will also propose an improvement in the microfabrication processes so that we can obtain the intense emission signals from the Bi-2223 mesas.