Current Modulation by Optoelectric Control of Ferroelectric Domains

Abstract

Optoelectric control of domains is likely to pave the foundation for optoferroelectric devices. This work reports the combined effect of light and lowvoltage electric bias for optoelectric control of ferroelectric domains in a semiconducting ceramic materialKNBNNO ((K 0.5 Na 0.5 )NbO 3 doped with 2 mol % Ba(Ni 0.5 Nb 0.5 )O 3−δ ). The effect is utilized to achieve two orders of magnitude amplification in electrical response, asymmetric AC modulation, and domain velocities of 30 000 nm s −1 with ultralarge domain switching areas of over 30 μm in fractions of a second. The charge injection due to light illumination on this material causes the tuning of material conductivity and acts as a virtual electrode. Based on this mechanism, a proof of concept for a monolithic ferroelectric light-effect transistor with a source and drain as electrical contacts with light acting as a virtual gate is demonstrated. This is likely to offer a potential solution to the scaling limit of conventional three-terminal transistors. The same device is also demonstrated to work as a photodiode, a half-wave rectifier, and an electrical output modulator.

Optomechanical Mapping of Ferroelectric Domains and the Piezo‐Photovoltaic Effect in Ba‐ and Ni‐Doped (K0.5Na0.5)NbO3

“…Similar observations (effect of various stimuli in the vicinity of the poled area) on KNBNNO samples have been observed by us due to electrical and electro‐optic poling. [ 31 ] This has not been fully understood by us due to the polycrystalline nature of this material. The out‐of‐plane PFM amplitude, when compared with the pristine state, shows significant variation as well, i.e., increases with increasing tip loading force (compare Figure 1m,n).…”

“…Apart from this, the specific preparation route can potentially cause the formation of a surface layer, which has been reported for other polycrystalline ferroelectric systems. [ 38 ] This also suggests that the reduction in the area of up domains on laser exposure, [ 7,30 ] applying electric field [ 31 ] and mechanical stress might be the inherent property of the material. Given that the piezoresponse changes significantly when the change in domain area is nominal (as shown in Figure 2b for 0.5–0.6 μN), it is highly likely that the asymmetry due to applied force cause diffusion and therefore leads to structural distortions.…”

“…KNBNNO is reported for an increase in conductivity due to 405 nm laser exposure and the effect increases by orders of magnitudes even with a small applied electric field. [ 31 ] However, in the present case, both measurements (with tip force of 0.07 and 1 μN) were performed under the same parameters and laser energy with no additional electric fields. This helps in ruling out the possibility of a decrease in serial resistance.…”

“…KNBNNO is an optically active material (bandgap of 1.6 eV) with a good piezoresponse. [ 12,29 ] It has been discussed with regard to nonthermal optical, [ 7,30 ] and optoelectric [ 31 ] control of ferroelectric domains. Based on a nominal change (<2 μC cm −2 ) in polarization over the broad temperature range (20–155 °C) and direct measurement of temperature (±0.5 °C) due to exposure of 405 nm wavelength illumination of our setup, we ruled out the possibility of localized heating and pyroelectric effect in KNBNNO in our previous studies.…”

“…Based on a nominal change (<2 μC cm −2 ) in polarization over the broad temperature range (20–155 °C) and direct measurement of temperature (±0.5 °C) due to exposure of 405 nm wavelength illumination of our setup, we ruled out the possibility of localized heating and pyroelectric effect in KNBNNO in our previous studies. [ 7,30,31 ] This makes it an ideal candidate for studying mechanical [ 32 ] and optomechanical control of ferroelectric domains as well. Nanoscale insight into the variation of the photovoltaic output due to optomechanical manipulation of ferroelectric domains is likely to lead to new opportunities in the area of ferroelectric–photovoltaics and opto‐ferroelectric [ 33 ] devices.…”