Effect of laser fluence on the ferroelectric properties of pulsed laser deposited (Pb 1− xLa x)Ti 1− x/4 O 3 thin films

Abstract

Dielectric thin films of (Pb 0.72La 0.28)Ti 0.93O 3 (PLT) have been deposited on Pt/Ti/SiO 2/Si substrates in situ by laser ablation. We have systematically investigated the effect of laser energy density on the ferroelectric properties of PLT thin films and the variation of grain sizes depending on the process conditions of a single-step deposition process and a two-step deposition process. Two-step deposition process was verified to be useful to enlarge the grain size of the film and to reduce the leakage current characteristics. PLT thin films on p-type (1 0 0) Si substrate were fabricated by pulsed laser deposition technique using a Nd:YAG laser with different energy densities of 1.5, 2.5 and 3.5 J/cm 2. The average grain sizes of the PLT thin films were successfully controlled from 80 to 130 nm by changing processing parameters. Structural properties and electrical properties including dielectric constant, ferroelectric characteristics and leakage current of PLT thin films were shown to be strongly influenced by grain size and laser energy density.