Observation of photo-dielectric effect in LaAl0.99Zn0.01O3-δ
Optical control of the resistivity and dielectric permittivity has been attracting much attention for application of next-generation optical-remote devices. Since the enhancement of the dielectric permittivity coincides with an increase in electrical conductivity in previous studies, the origin is the contribution of the photo-excited carriers. The increase in electrical conductivity, however, corresponds to the energy loss in a capacitor. Thus, a new method to enhance the dielectric permittivity via photo-irradiation has been required.
Here, we demonstrate photo-induced enhancement of the dielectric permittivity without an increase in electrical conductivity in the high-frequency region in Zn-doped LaAlO3. Since the light energy is much lower than the bandgap energy, the phenomena are related to trapping of the photo-excited electrons in the impurity levels introduced by Zn substitution. These findings are expected to contribute to the development of photo-capacitors that enable the remote control of the dielectric response via photo-irradiation.
"Optical Control of Dielectric Permittivity in LaAl0.99Zn0.01O3-δ"
by T. Nagai, H. Takahashi, R. Okazaki, K. Tanabe, I. Terasaki, and H. Taniguchi
Applied Physical Letters 110 (2017) 172901.
(AIP publishing)
(Figure) Variation of the dielectric permittivity of LaAl0.99Zn0.01O3-δ by ultraviolet illumination.
Here, we demonstrate photo-induced enhancement of the dielectric permittivity without an increase in electrical conductivity in the high-frequency region in Zn-doped LaAlO3. Since the light energy is much lower than the bandgap energy, the phenomena are related to trapping of the photo-excited electrons in the impurity levels introduced by Zn substitution. These findings are expected to contribute to the development of photo-capacitors that enable the remote control of the dielectric response via photo-irradiation.