Nanocrystalline Ge films created by thermal vacuum deposition on GaAs substrates: structural and electric properties

The technique of thermal vacuum deposition of Ge onto GaAs substrates has been used for obtaining nanocrystalline Ge films. Nanocrystalline character of the films is confirmed by atomic force microscopy of their surface and by the data of Raman light scattering. The most probable size of the nanocrystallites forming the films decreases monotonically with decreasing their thickness. Electro conductivity of such the films proves to be high enough (1-10 Ohm.cm at room temperature) and has a character of variable range hopping conduction of Mott's type. The hops, presumably, take place through the localized states connected with the grain boundaries.