title: Surface charges and optical characteristic of colloidal cubic SiC nanocrystals.
abstract: Colloidal cubic silicon carbide (SiC) nanocrystals with an average diameter of 4.4 nm have been fabricated by anisotropic wet chemical etching of microsized cubic SiC powder. Fourier transform infrared spectra show that these cubic SiC nanocrystals contain carboxylic acid, SiH, CH, and CHx groups. UV/Vis absorption and photoluminescence (PL) spectroscopy clearly indicate that water and ethanol colloidal suspensions of the as-fabricated colloidal samples exhibit strong and above band gap blue and blue-green emissions. The cubic SiC nanocrystals show different surface charges in water and ethanol solutions due to the interaction of water molecules with polar Si-terminated surfaces of cubic SiC nanocrystals. The results explain the distinctive optical characteristics of colloidal cubic SiC nanocrystals in water and ethanol, and reveal that quantum confinement and surface charges play a great role in determining the optical characteristics of colloidal cubic SiC nanocrystals.
authors.affiliation: Technical Institute of Physics and Chemistry, Chinese Academy of Science, Beijing 100190, PR China. chen.c.x@sjtu.edu.cn.
authors.forename: Yong
authors.initials: Y
authors.lastname: Li
authors.forename: Changxin
authors.initials: C
authors.lastname: Chen
authors.forename: Jiang-Tao
authors.initials: JT
authors.lastname: Li
authors.forename: Yun
authors.initials: Y
authors.lastname: Yang
authors.forename: Zhi-Ming
authors.initials: ZM
authors.lastname: Lin