The effect of the donor dopant $La^{3+}$ on physical properties in the $SrTi_{1.015}O_3$ system, which has been a common base material of the barrier layer (BL) capacitor, was studied by means of X-ray diffractometer, optical microscopy, capacitance, and resistance measurements.
The semiconducting ceramic body was manufactured by the process of sintering in the atmosphere of 95Ar+$5H_2$ (flow rate : 100 cc/min). The insulating oxide mixture, 50w/oPbO-45w/$oBi_2O_3$-5w/o $B_2O_3$ was introduced this semiconducting body by the vapor phase diffusion method at 1000℃ in air. The initially sintered semiconducting bodies have the bulk resistivity of $10^1-10^2$ohm.cm which decreases with the increasing concentration of La in the $La_xSr_{1-x}Ti_{1.015}O_3$ system.
The oxide in-diffused final dielectric bodies represent PTCR below the resistivity maximum temperature which decreases with the increase of the La content. The temperature characteristics of the permittivity and loss factor of these final BL capacitors is dependent on the amount of the La, and their temperature coefficient varies from negative to positive value as La concentration increases. The BL capacitors obtained in this study have K'=4000-28000 and tanδ=0.05-0.09.
