Layer-resolved ultrafast extreme ultraviolet measurement of hole transport in a Ni-TiO 2 -Si photoanode.

Autor: Cushing SK; Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA., Molesky; Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA.; Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA., de Roulet BR; Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA., Lee A; Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA., Marsh BM; Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA., Szoke S; Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA., Vaida ME; Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA.; Department of Physics, University of Central Florida, Orlando, FL 32816, USA., Leone SR; Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA.; Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.; Department of Physics, University of California, Berkeley, Berkeley, CA 94720, USA.
Jazyk: angličtina
Zdroj: Science advances [Sci Adv] 2020 Apr 03; Vol. 6 (14), pp. eaay6650. Date of Electronic Publication: 2020 Apr 03 (Print Publication: 2020).
DOI: 10.1126/sciadv.aay6650
Abstrakt: Metal oxide semiconductor junctions are central to most electronic and optoelectronic devices, but ultrafast measurements of carrier transport have been limited to device-average measurements. Here, charge transport and recombination kinetics in each layer of a Ni-TiO 2 -Si junction is measured using the element specificity of broadband extreme ultraviolet (XUV) ultrafast pulses. After silicon photoexcitation, holes are inferred to transport from Si to Ni ballistically in ~100 fs, resulting in characteristic spectral shifts in the XUV edges. Meanwhile, the electrons remain on Si. After picoseconds, the transient hole population on Ni is observed to back-diffuse through the TiO 2 , shifting the Ti spectrum to a higher oxidation state, followed by electron-hole recombination at the Si-TiO 2 interface and in the Si bulk. Electrical properties, such as the hole diffusion constant in TiO 2 and the initial hole mobility in Si, are fit from these transient spectra and match well with values reported previously.
(Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).)
Databáze: MEDLINE
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