Novel High Tc Superconducting Junction by Plasma-Enhanced Chemical Vapor Deposition

The availability of high-quality HTSC junction has direct implications in the development of quantum IR detectors and other electronic and optoelectronic applications. A novel piezoelectric BaTiO3/superconducting YBCO/bicrystal SrTiO3 grain boundary junction is proposed to be demonstrated in this program. This hybrid junction structure in which the tunneling space between the two grains can be tuned to achieve the optima performance via stress induced by a piezoelectric layer, potentially offers a viable scheme to high performance SIS junction. Currently, an advanced materials processing technology capable of controlling the mircrostructures of HTSC thin films is desirable for both scientific evaluations and practical applications of HTSC technology. In this program we propose to develop an innovative plasma-enhanced chemical vapor deposition process (PE-CVD), which can potentially reduce twining by growing the orthorhombic superconducting phase in the as deposited state at low temperatures and reducing defects by suppressing the formation of impurities via a selective plasma etching technique. Moreover, PE-CVD is an attractive process due to its large-area, low temperature, high growth rate, and low cost fabrication capabilities. Phase I work will emphasize the feasibility demonstration of epitaxially growing the multilayer junction structure by the PE-CVD process.