Resistance degradation in barium strontium titanate thin films

Citation
S. Zafar et al., Resistance degradation in barium strontium titanate thin films, J APPL PHYS, 86(7), 1999, pp. 3890-3894
Citations number
13
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science
Journal title
JOURNAL OF APPLIED PHYSICS
ISSN journal
00218979 → ACNP
Volume
86
Issue
7
Year of publication
1999
Pages
3890 - 3894
Database
ISI
SICI code
0021-8979(19991001)86:7<3890:RDIBST>2.0.ZU;2-J
Abstract
Experimental and modeling results for resistance degradation in thin Ba0.5S r0.5TiO3 (BST) film capacitors with platinum (Pt) electrodes are reported. The main experimental results are as follows. Under a constant applied volt age, the current density is observed to increase with time until it reaches a maximum value. Once the maximum value is reached, the current density be comes constant with time. The barrier height at the BST/Pt (cathode) interf ace is observed to decrease after prolonged electrical stressing. The resis tance degradation effect is observed to be reversible, particularly at elev ated temperatures. Based on the experimental results, a quantitative model for resistance degradation is proposed. In this model, the increase in the current density is attributed to a decrease in the barrier height at the ca thode and this decrease is assumed to have a stretched exponential dependen ce on time. Using experimentally determined parameters, the model calculate s the current density as a function of time at various temperatures. The ca lculated results are verified and the model is shown to be self-consistent. Hence the model provides an accelerated method for determining the lifetim e of thin BST films at the operating conditions for advanced memory applica tions. (C) 1999 American Institute of Physics. [S0021-8979(99)06217-9].