Variation of electrical conduction phenomena of Pt/(Ba, Sr)TiO3/Pt capacitors by different top electrode formation processes

Electrical conduction behaviors of Pt/(Ba, Sr)TiO3/Pt thin him capacitors having top Pt electrodes with different deposition powers are investigated. The capacitors having top Pt electrode with deposition power of 0.2kW show Schottky emission behavior at both top and bottom electrode interfaces with potential barrier heights of 1.24-1.48 eV and 1.88-2.08 eV, respectively. However, the capacitor having top Pt electrode with larger deposition power of 0.5kW shows Schottky emission behavior only at bottom electrode interface with barrier of 1.61-1.89eV. Interface with top electrode appears to have very low resistance, and a positive temperature coefficient of resistivity (PTCR) effect is observed when the electrons are injected ham the top electrode to bottom electrode through BST film. Tap Pt electrode becomes very rough by grain growth during postannealing when the top Pt is deposited with powers of larger than 0.5kW. Roughening of the top Pt results in the low-resistance contact behavior at the interface between top Pt and BST, which results in PTCR effect.