Using High Frequency LIMM to characterize the poling state of piezoelectric ceramic thin films

ABSTRACTThe Laser Intensity Modulation Method, LIMM, has been used to investigate the poling state of ceramic piezoelectric thin films. The frequency of the system has been extended to 70MHz to enable films of thicknesses down to 100nm to be measured. A unique development has been to sweep the DC bias applied to the sample whilst performing the LIMM measurement, thus giving pseudo PE loops. These PE loops are unique in that they represent the polarization state within a distinct depth of the film, whereas normally PE loops are a result of the complete film. This allows us to investigate processes occurring within different regions of the film.