Silicon carbide (SiC) single crystals, along with sapphire and silicon, are one of
the most important substrates for high-brightness light-emitting diode fabrications.
Owing to extremely high hardness (Mohs’ scale of 9.5) and chemical inertness, the
polishing rate of SiC with conventional chemical mechanical polishing methods is not
high, and surface scratches are also inevitable because of using slurry containing
hard abrasives such as silica particles. Here artemisinin (Qinghaosu) crystals, very
soft molecular solids, were found, for the first time to the best of our knowledge,
to effectively polish SiC wafers even in pure water as demonstrated by proof-of-concept
scratching experiments using atomic force microscopy. The underlying mechanism is
attributed to activated oxidation of SiC by mechanically released reactive · OH free
radicals from the endoperoxide bridges. The preliminary results reported here have
important implications for developing novel alternative green and scratch-free polishing
methods for hard-brittle substrates including SiC, diamond, and others.