Conduction and trapping mechanisms in monocrystalline titanium dioxide through the mirror method

The present work deals with the use of the Scanning Electron Microscope Mirror method (SEMM method) for characterizing the conduction and trapping mechanisms in the monocrystalline rutile (TiO₂). First, the SEMM characterizations shows that monocrystalline rutile traps strong quantity of electric charges, depending on the preliminary thermal and mechanical treatments, like for sapphire. However, one of the most interesting results is the unusual shape of the mirror image. Indeed, instead of being circular the mirrors images are elliptic, leading to the idea that the anisotropy of the material could play an important role on the conduction and trapping mechanisms. This idea is confirmed by the evolution of the curved part of the typical mirror plot 1/d=f(V). This curved part, interpreted for example in a model of multipole approximation, clearly shows an anisotropic shape of the distribution geometry of the charges. Finally, correlations with the presence of dislocations, as preferential way of electron conduction and (or) traps will be made to explain this anisotropic shape.