Linear, paraelectric (Pb0.72La0.28)TiO3 or PLT(28) thin films with a bandgap > 3 eV were deposited on Pt/Ti/SiO2/Si substrates by the sol-gel technique. Specific top-contact metals from two distinct groups (i.e., non-noble or MT and noble or MN; the former being oxidizable transition metals) were selected to understand the electrical nature of the interfaces in terms of electrode dependent energy band diagrams and equivalent circuit models. Using a high sensitivity high-pass filter circuit to evaluate the charging and discharging behavior coupled with results of the thickness and voltage dependence of capacitance, it was determined that MT (Ni, Cr, Ti) and MN (Pt, Au, Ag) metals form Ohmic and Schottky contacts, respectively. Supported by thermochemical data and calculations, the ohmic MT-PLT interfaces are envisioned to be of the form: MT-MTOx-n+PLT-nPLT. In contrast, the MN-PLT interfaces may be characterized by a metal work function independent Schottky diode; the surface Fermi level being pinned at the mid-gap. For example, a Schottky barrier height of 1.83 eV and a built-in voltage of 1.3 eV at the Pt-PLT interface were estimated. From low field capacitance measurements, the ratio of interfacial to bulk resistance, Ri/Rb, was estimated to be 23.
|Original language||English (US)|
|Title of host publication||Japanese Journal of Applied Physics, Part 1: Regular Papers & Short Notes & Review Papers|
|Place of Publication||Minato-ku, Japan|
|Number of pages||11|
|State||Published - Jun 1995|
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