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.
Highlights
Silicon carbide (SiC) is an important wide band gap semiconductor with superior properties, such as excellent thermal conductivity, high breakdown field strength, and excellent physical and chemical stability [1,2,3,4]
Zhu and coworkers have reported the synthesis of cubic SiC nanocrystals by wet electroless etching of microscale cubic SiC powder in a HNO3/hydrofluoric acid (HF) solution and experimentally observed intense violet-blue photoluminescence (PL) from colloidal cubic SiC nanocrystals [16]
We report successful fabrication of colloidal cubic SiC nanocrystals by anisotropic wet chemical etching of microsized cubic SiC powder
Summary
Silicon carbide (SiC) is an important wide band gap semiconductor with superior properties, such as excellent thermal conductivity, high breakdown field strength, and excellent physical and chemical stability [1,2,3,4]. Recent advances in the preparation of SiC nanocrystals have paved the way for wider uses in microelectronic cubic SiC powder, and subsequent ultrasonic vibration [16], and so on. Among these methods, catalyzed electrochemical etching of polycrystalline SiC wafers in a hydrofluoric acid (HF)/ethanol solution is most intensively investigated [17,18]. Zhu and coworkers have reported the synthesis of cubic SiC nanocrystals by wet electroless etching of microscale cubic SiC powder in a HNO3/HF solution and experimentally observed intense violet-blue photoluminescence (PL) from colloidal cubic SiC nanocrystals [16]. The surface chemistry of etched cubic SiC powder from which cubic SiC nanocrystals derived and the influence of surface terminations of cubic SiC nanocrystals in different surrounding environments on its optical properties still need to be investigated in detail
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