(0001) quartz surface imperfections

Overview & Synopsis

Monocrystalline (0001) quartz surfaces may present two kinds of imperfections : point defects (surface oxygen vacancies) and tridimensional disorder (superficial amorphization). The point defects are studied thanks to Refection Electron Energy Loss Spectroscopy experiments, which show that electronic transitions (5.1 and 7.2 eV) associated with surface oxygen vacancies appear in the gap of α-quartz under ion or electron bombardment and 900°C vacuum heating. The defects responsible for these structures are located in the first nm under the surface. X-ray Absorption Near Edge experiments (XANES) at the O K-edge show that the 900°C vacuum heating leads moreover to the destruction of the surface crystallinity (≈5nm), as proved by the modification of the multiple scattering structures.