B. Nagaraj et al., (BaSr)TiO3 thin films with conducting perovskite electrodes for dynamic random access memory applications, APPL PHYS L, 74(21), 1999, pp. 3194-3196
Interfaces and hence electrodes determine the performance of (Ba,Sr)TiO3 (B
ST) capacitors for ultralarge scale integration dynamic random access memor
ies. Electrode materials forming a rectifying contact on BST drastically re
duce the dielectric constant and hence the capacitance and charge storage d
ensity of the capacitor, when the dielectric thickness is reduced. This can
limit the role of Pt as an electrode material for gigabit dynamic random a
ccess memories (DRAM). The conducting oxide, La0.5Sr0.5CoO3 (LSCO) with its
perovskite structure, has structural and chemical compatibility with BST.
Our results in LSCO/BST/LSCO capacitor show that the mechanism of conductio
n is not interface limited but predominantly bulk limited. A 75 nm BST film
with LSCO electrodes shows a leakage current density of 1 X 10(-7) A/cm(2)
at 1 V, 85 degrees C. The dielectric constant at 1 V, 10(5) Hz is 350, mak
ing LSCO a potential contact electrode for DRAM memories. (C) 1999 American
Institute of Physics. [S0003-6951(99)00821-9].