Effect of processing parameters and substrate on the preferred orientation of Sol-Gel calcium modified lead titanate thin films

摘要

In this work the characteristics of the texture of sol-gel Pb_0.76Ca_0.24TiO_3 deposited onto three differentsubstrates: Pt/ Ti/ SiO_2/ Si, Ti/ Pt/ Ti/SiO_2 / Si y Pt/ TiO_2/SiO_2 /Si, are studied. The films were prepared by spin-coatingthe precursor solution, with a low concentration. onto thesubstrates and by further drying at 350beg C and crystallisation at650beg C, with a heating rate of ~30.4sbeg C/s. Each of thedeposited layers had a thickness of ~75 nm. Four successive layerswere deposited to obtain a film thickness of ~300 nm. Texture ofthe Pb_0.76Ca_0.24TiO_3 films on the different substrates wasstudied by means of X-ray diffraction. The crystalline phasespresent at the substrates surfaces were identify by means of grazingincidence X-ray diffraction. The Pb_0.76Ca_0.24TiO_3 film 0nthe Ti/Pt/Ti/SiO_2/Si substrate developed a <111> preferredorientation. A spontaneous pyroelectric coefficient of #gamma#~-6.49X10~-9Ccm~-2K~-1 was measured in this sample.