Electrical properties of nanostructured germanium and nanocomposite germanium-fullerene C60 materials

Nanostructured Germanium and nanocomposite germanium-fullerene C60 samples are synthesized by ball-milling and hot sintering under pressure with C60 content up to 9 vol/%. The structure and electrical properties (electrical conductivity, the Hall mobility and free charge carrier density) are studied. The fullerene C60 prevents the recrystallization of samples during sintering and allow us to vary the mean crystalline size of Ge nanoparticles in the range of 15 to 100 nm. The electrical conductivity of the fullerene-free and Ge-C60 nanocomposites increases by several times. The nonmonotonic dependencies of the electric conductivity and the Hall mobility of free charge carriers on l value have been observed. Such (l ) and (l ) dependencies can occur due to the high density of defect vacancies on the grain boundaries and the quantum-size effect.