Direct Observation of Hydrogen Etching Anisotropy on Diamond Single Crystal Surfaces

Etching of natural diamonds by atomic hydrogen has been investigated on C(100), C(110), and C(111) single crystal surfaces. Infrared absorption spectroscopy and low-energy electron diffraction provide direct evidence for an etching anisotropy at 1100 K. The results indicate that, in the presence of atomic hydrogen, $\{111\}$-oriented facet formation irreversibly occurs on both C(110) and C(100), whereas C(111) remains intact. The finding has important implications for chemical vapor deposition diamond synthesis and H-plasma surface polishing.