Positive temperature coefficient of resistivity in Pt/(Ba_(0.7)Sr_(0.3))TiO_(3)/YBa_(2)Cu_(3)O_(7-x) capacitors

摘要

Pt/(Ba_(0.7)Sr_(0.3))TiO_(3)(BST)/YBa_(2)Cu_(3)O_(7-x)(YBCO) capacitors were fabricated on (001) LaAlO_(3) substrates. The leakage current density-electric field characteristics were measured in the temperature range from 20 to 300 K. In the electric field region of >0.7 MV/cm for positively biased Pt electrode and >1.4 MV/cm for negatively biased Pt electrode, the leakage current shows space-charge-limited-current behavior from 20 to 250 K. Meanwhile a positive temperature coefficient of resistivity (PTCR) in the temperature range from 20 to 150 K was observed and attributed to the strong negative temperature dependence of the dielectric constant of BST thin films.