How to measure intrinsic low frequency noise in thin film samples?

The measurement of low frequency noise can be considered as an important part in optimization of sensor noise-signal ratio. But sometimes, the intrinsic low frequency noise is affected by contact noise, which can be generated by geometrical defect of thin film. Thus, the measured noise level could not reveal material properties. We report different low frequency noise measurement methods in a general geometry sample of thin film. A detailed analysis of noise measurement has been described by relative equations. Finally, a discussion has been investigated in systematic measurements of low frequency noise at room temperature in La_0.7Sr_0.3MnO₃(LSMO) thin films and noise measurements are presented by noise spectral densities as function of frequency.