Electrical Characterisation CV, IV

For the measurements of the ferroelectric hysteresis of P(VDF-TrFE) via the flatband shift, we used capacitors with oxidised p-type (-lO cm ) silicon substrate (100-235 nm Si02) to prevent large amoimts of leakage current. The copolymer film was prepared as described above. We used films of thickness fiom 100 nm to 1 pm. The structiues were prepared in top electrode geometry , with thermal evaporated aluminium, patterned via a shadow mask. The measiuements of capacitance versus voltage (CV) were carried out with an Agilent 4284A LCR meter at a frequency of 1 MHz with sweep rates fiom 

5 mV/s to 50 mV/s. Here, we present high-frequency investigations of these structures in the low-frequency mode we find the same effect [16]. 

All measurements were started in accumulation and finished there too, after driving the voltage in the investigated range to inversion and back (e.g. -10 V to 10 V and backwards to -10 V we call this a 10 V loop ). Due to the polarisation of the ferroelectric layer, the CV curves show a hysteresis loop [30, 31], which depends on the maximal applied voltage in the CV mode. 

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