Non-volatile optical switch of resistance in photoferroelectric tunnel junctions

Abstract

In the quest for energy efficient and fast memory elements, optically controlled ferroelectric memories are promising candidates. Here, we show that, by taking advantage of the imprint electric field existing in the nanometric BaTiO3 films and their photovoltaic response at visible light, the polarization of suitably written domains can be reversed under illumination. We exploit this effect to trigger and measure the associate change of resistance in tunnel devices. We show that engineering the device structure by inserting an auxiliary dielectric layer, the electroresistance increases by a factor near 2 × 103%, and a robust electric and optic cycling of the device can be obtained mimicking the operation of a memory device under dual control of light and electric fields.

Control of up-to-down/down-to-up light-induced ferroelectric polarization reversal

“…48 In both cases, the polarization is unstable under illumination and the subsequent reduction of available photocarriers when the light stimulus is off results in the alignment of the ferroelectric polarization with the internal electric fields. 44 The PFM measurements described above provide rather compelling evidence that illumination promotes the reversal of the ferroelectric polarization direction at the BTO film surface. However, it would be reassuring to use an additional probe directly related to the ferroelectric polarization of the ferroelectric layer.…”

“…S9 and S10, ESI†), further disregarding the important contribution of heating effects and indicating that the polarization switch is driven by photocarrier generation as claimed in previous works. 44 In addition, the absence of switching under red illumination in the BTO/LSMO and BTO/SRO samples also indicates that the light absorption and concomitant photocharge generation at the electrode, which should occur at this wavelength, because the LSMO and SRO bandgaps are smaller ( E g,SRO = 0.27 eV 45 and E g,LSMO = 0.63 eV 46 ) than the energy of the red photons ( E red = 1.94 eV), does not have an impact on the P switch under illumination. Therefore, photocarriers generated at the BTO layer are at the origin of the P switch under illumination.…”

“…48 In both cases, the polarization is unstable under illumination and the subsequent reduction of available photocarriers when the light stimulus is off results in the alignment of the ferroelectric polarization with the internal electric fields. 44…”

Ultrasensitive Ferroelectric Semiconductor Phototransistors for Photon‐Level Detection

“…This phenomenon has been found in individual BaTiO 3 and MoS 2 /BaTiO 3 heterostructure, which is ascribed to the existence of imprint electric field coming from defects and interfacial states. [29][30][31][32][33] This imprint electric field will make the energy minima in the double-well energy landscape asymmetry and favor a particular polarization direction. [30,[34][35][36][37] Here, the favored and stable direction of α-In 2 Se 3 is polarization down.…”

Ferroelectric BaTiO3 Based Multi‐Effects Coupled Materials and Devices

“…exhibited light controlling written domain polarization through the coupling of the photovoltaic response and imprint electric field of ultrathin BaTiO 3 films, which were used for the induction and measurement of resistance change of tunnel devices. [ 148 ]…”