Photocapacitance change in YMnO₃ based MFIS in the visible light regime

YMnO₃ is one of the few materials that exhibit ferroelectricity and antiferromagnetism. Metal-YMnO₃-metal thin film structures can be switched between a high resistance state (HRS) and a low resistance state (LRS), when a positive and negative writing bias is applied, respectively. This work investigates the effect of light-irradiation on the capacitance of YMnO₃-based metal-ferroelectric-insulatorsemiconductor (MFIS) structures. The DC bias for the capacitance measurements was swept from +10 to -20 V and back under different light-irradiation at a sweep rate of ca. 103 mV/s. It has been found that under dark conditions two nonvolatile capacitance minima exists at -11 and at -3.55 V, possibly when the YMnO₃ is in the LRS and HRS state, respectively. If we rewrite the +10 and -20 V branch in shorter period of time then, low capacitance state (LCS) is non-volatile and pseudo volatile, respectively. Under illumination the capacitance at the two minima increases in the visible spectral range, depending on the wavelength illumination, YMnO₃ thickness and YMnO₃ capacitance state.