Micrometer-thick perovskite-type multilayer heterostructures with ten thousands of unit cells, [SrNb0.05Ti0.95O3∕La0.9Sr0.1MnO3]3, have been fabricated on Si substrates. The structure exhibited nonlinear and rectifying current-voltage characteristics. Stable and temporal photovoltaic effects in the multilayer have been experimentally studied by using different wavelength light sources from ultraviolet to infrared, respectively. The photovoltage and photocurrent responsivities as a function of wavelength displayed that two cutoff wavelengths occurred corresponding to the band gaps of SrNb0.05Ti0.95O3 and Si and La0.9Sr0.1MnO3. Under the pulsed laser illumination the nanosecond response characterization of the present multilayer structure was obtained. Based on the band structure of the multilayers, a possible mechanism of photovoltaic process was proposed.

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Pressure-dependent terahertz optical characterization of heptafluoropropane *Leng Wen-Xiu(冷文秀) a)b) † , Ge Li-Na(戈立娜) c) , Xu Shan-Sen(徐山森) d) , Zhan Hong-Lei(詹洪磊) c) , and Zhao Kun(赵 昆) a)b)c) ‡ a

Optical assessment of oil shale using terahertz time-domain spectroscopy (THz-TDS) was carried out to study oil potential. Fischer assay testing was employed to obtain the oil yield of oil shale specimens to examine the difference of oil potential between oil shale samples from three regions: Beipiao, Barkol, and Huadian in China. Then, two types of specimens from each area were prepared for the optical tests and the results were compared. The refractive index (n) at 0.2–1.2 THz was derived; n decreased slowly with increasing frequency for all the specimens despite the oscillation pattern observed at lower frequencies. The specimen preparation method that mixed the powdered material led to minor differences between the specimens. The different response of kerogen to the terahertz pulse depending on the kerogen's evolutionary stage leads to a difference in the refractive index between the specimens from the various regions. This study indicates that using THz-TDS to evaluate the oil content in oil shale without inducing reaction within the specimen can be an effective method for resource exploration.