Abstract-Broadband ultra-high transmission of terahertz radiation through monolayer MoS2

Xue-Yong Deng^1,2, Xin-Hua Deng³, Fu-Hai Su⁴, Nian-Hua Liu^1,3 andJiang-Tao Liu^1,3,a)
 HIDE AFFILIATIONS
1 Nanoscale Science and Technology Laboratory, Institute for Advanced Study, Nanchang University, Nanchang 330031, China
2 Materials Science and Engineering, Nanchang University, Nanchang 330031, China
3 Department of Physics, Nanchang University, Nanchang 330031, China
4 Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China
a) Electronic mail: jtliu@semi.ac.cn
J. Appl. Phys. 118, 224304 (2015); http://dx.doi.org/10.1063/1.4937276
http://scitation.aip.org/content/aip/journal/jap/118/22/10.1063/1.4937276?TRACK=RSS

We used time-resolved terahertz spectroscopy to study ultrafast photoconductivity of polycrystallinethin-film silicon solar cells. We selected a series of samples, which exhibited variable conversion efficiencies due to hydrogen plasmapassivation under various technological conditions. The decay of the transient terahertz conductivity shows two components: the fast one is related to the charge recombination at interfaces, while the slow nanosecond one is attributed to the trapping of photocarriers by defects localized at grain boundaries or at dislocations in the polycrystalline p⁻ layer of the structure. We observed a clear correlation between the open-circuit voltage and the nanosecond-scale decay time of the transient terahertz conductivity of the solar cells. Thus, the terahertz spectroscopy appears to be a useful contactless tool for inspecting the local photoconductivity of solar cells including, in particular, various nanostructured schemes.

Abstract-Gate-tunable nearly total terahertz absorption in graphene with resonant metal back reflector

Jiang-Tao Liu, Nian-Hua Liu, Li Wang, Xin-Hua Deng, Fu-Hai Su

(Submitted on 9 Nov 2013)

http://arxiv.org/abs/1311.2120

The gate-tunable terahertz (THz) absorption of graphene layers with a resonant metal back reflector (RMBF) is theoretically investigated. We demonstrate that the THz absorption of graphene with RMBF can vary from nearly negligible to nearly total by tuning the external gate voltage. This peculiar nearly total THz absorption can be attributed to the Fabry-Perot cavity effect, which enhances the absorption and reduces the reflection of graphene. The absorption spectra of the graphene-RMBF structure can also be tailored in bandwidth and center frequency by changing the thickness and dielectric constant of the spacer layer.