Electrical Properties of Paraelectric (Pb0.72La0.28)TiO3Thin Films with High Linear Dielectric Permittivity: Schottky and Ohmic Contacts

Autor: Dey, Sandwip K., Lee, Jong-Jan, Prasad Alluri, Prasad Alluri
Zdroj: Japanese Journal of Applied Physics; June 1995, Vol. 34 Issue: 6 p3142-3142, 1p
Abstrakt: Linear, paraelectric (Pb0.72La0.28)TiO3or 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 MTand 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.
Databáze: Supplemental Index
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