Materials Research Institute, The Pennsylvania State University, University Park, PA, USA.
IEEE Trans Ultrason Ferroelectr Freq Control. 2010 Oct;57(10):2182-91. doi: 10.1109/TUFFC.2010.1676.
The crystallization kinetics of laser-annealed Lamodified Pb(Zr,Ti)O₃ (PLZT) thin films on LaNiO₃-coated silicon substrates were investigated for substrate temperatures below 400 °C. A KrF excimer laser having a ~20 ns pulse width and an energy density ~40 mJ/cm² was used to crystallize the films. The perovskite phase developed with cumulative laser pulse exposures; it was found that ~380 to 400 nm thick films could be fully crystallized for a total exposure time of 0.1 to 1 ms. Laser-crystallized films exhibited comparable dielectric and ferroelectric properties to those prepared by rapid thermal annealing at 650 °C for 1 min. The evolution of the dielectric properties as a function of the number of laser strikes suggests that once nuclei are present, they rapidly grow through the depth of the film. This is consistent with the electron microscopy results, which did not show a well-defined planar growth front that proceeds from the top to the bottom of the film. The resulting films showed comparatively large lateral grain sizes (on the order of 250 to 300 nm), with high defect concentrations. The nucleation and growth mechanisms were modeled using Avrami kinetics under rate-dependent and nonisothermal conditions. These results indicate that PLZT crystallization via laser annealing is nucleation-limited.
在低于 400°C 的衬底温度下，研究了激光退火的 Lamodified Pb(Zr,Ti)O₃（PLZT）薄膜在 LaNiO₃ 涂层硅衬底上的结晶动力学。使用具有约 20 ns 脉冲宽度和约 40 mJ/cm² 能量密度的 KrF 准分子激光器来使薄膜结晶。钙钛矿相随着累积激光脉冲曝光而发展；发现对于总曝光时间为 0.1 至 1 ms 的约 380 至 400nm 厚的薄膜可以完全结晶。与在 650°C 下快速热退火 1 分钟制备的薄膜相比，激光结晶的薄膜表现出相当的介电和铁电性能。随着激光冲击次数的增加，介电性能的演变表明，一旦存在晶核，它们就会迅速在薄膜的深度方向上生长。这与电子显微镜结果一致，电子显微镜结果没有显示出从薄膜顶部到底部进行的明确的平面生长前沿。所得薄膜显示出相对较大的横向晶粒尺寸（约 250 至 300nm），并且具有较高的缺陷浓度。使用依赖于速率的和非等温条件下的 Avrami 动力学对成核和生长机制进行了建模。这些结果表明，通过激光退火的 PLZT 结晶是受成核限制的。
