High-throughput growth temperature optimization of ferroelectric Sr_(x)Ba_(1-x)Nb_(2)O_(6) epitaxial thin films using a temperature gradient method

摘要

We have developed a multisample film growth method on a temperature-gradient substrate holder to quickly optimize the film growth temperature in pulsed-laser deposition. A smooth temperature gradient is achieved, covering a range of temperatures from 200 to 830℃. In a single growth run, the optimal growth temperature for Sr_(x)Ba_(1-x)Nb_(2)O_(6) thin films on MgO(001) substrates was determined to be 750℃, based on results from ellipsometry and piezoresponse force microscopy. Variations in optical properties and ferroelectric domains structures were clearly observed as function of growth temperature, and these physical properties can be related to their different crystalline quality. Piezoresponse force microscopy indicated the formation of uniform ferroelectric film for deposition temperatures above 750℃. At 660℃, isolated micron-sized ferroelectric islands were observed, while samples deposited below 550℃ did not exhibit clear piezoelectric contrast.