1. Controlling the surface photovoltage on WSe2 by surface chemical modification
- Author
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Kenichi Ozawa, Suguru Ito, Naoya Terashima, Wei Chuan Chen, Susumu Yamamoto, Iwao Matsuda, Tai-Chang Chiang, Baojie Feng, Ro-Ya Liu, Cheng Maw Cheng, Yuto Natsui, and Hiroo Kato
- Subjects
chemistry.chemical_classification ,Materials science ,Physics and Astronomy (miscellaneous) ,Surface photovoltage ,Electron donor ,02 engineering and technology ,Carrier lifetime ,Electron acceptor ,021001 nanoscience & nanotechnology ,Photochemistry ,01 natural sciences ,chemistry.chemical_compound ,Adsorption ,Transition metal ,chemistry ,0103 physical sciences ,Surface chemical ,010306 general physics ,0210 nano-technology ,Recombination - Abstract
The surface photovoltage (SPV) effect is key to the development of opto-electronic devices such as solar-cells and photo-detectors. For the prototypical transition metal dichalcogenide WSe2, core level and valence band photoemission measurements show that the surface band bending of pristine cleaved surfaces can be readily modified by adsorption with K (an electron donor) or C60 (an electron acceptor). Time-resolved pump-probe photoemission measurements reveal that the SPV for pristine cleaved surfaces is enhanced by K adsorption, but suppressed by C60 adsorption, and yet the SPV relaxation time is substantially shortened in both cases. Evidently, adsorbate-induced electronic states act as electron-hole recombination centers that shorten the carrier lifetime.
- Published
- 2018