Abstract

Surface charge transfer doping (SCTD) hasemerged as an efficient approach to tune the electrical and optical propertiesof semiconductor nanostructures. As an important II-VI semiconductor, cadmiumsulfide (CdS) nanostructures possess superior optoelectronic properties.However, SCTD on the CdS nanostructures remains a challenge, and the underlyingmechanism for optical property modulation is unclear. Herein, we demonstratethat both the electrical and Raman scattering properties of CdS nanoribbons(NRs) can be tuned by using MoO3 and benzyl viologen (BV) as surface dopants.The MoO3 (or BV) molecules, which have high work function (or strong reducingcapability), can extract (or inject) electrons from (or into) the CdS NRsbecause of the large difference in energy levels, leading to the electrondepletion (or accumulation) within the CdS NRs. By controlling the amount ofsurface dopants, the electron concentration as well as resistivity of the CdSNRs can be readily modulated. Significantly, Raman scattering properties of theCdS NRs can be fine-tuned due to strong electron-phonon coupling effect. Amechanism based on the semi-classical longitudinal-optical-phonon-plasmontheory is first proposed to explain the SCTD-induced Raman scatteringmodulation. Our findings offer a feasible route for modulation of electricaland optical properties of compound semiconductor nanostructures.