Annealing Effect on Magnetic and Electrical Properties of Amorphous Ge1-xMnx Thin Films

Amorphous Ge1-xMnx semiconductor thin films grown by low temperature vapor deposition were annealed, and their electrical and magnetic properties have been studied. The amorphous thin films were 1,000 similar to 5,000 angstrom thick. Amorphous Ge1-xMnx thin films were annealed at 300 degrees C, 400 degrees C, 500 degrees C, 600 degrees C and 700 degrees C for 3 minutes in high vacuum chamber. X-ray diffraction analysis reveals that as-grown Ge1-xMnx semiconductor thin films are amorphous and are crystallized by annealing. Crystallization temperature of amorphous Ge1-xMnx semiconductor thin films varies with Mn concentration. Amorphous Ge1-xMnx thin films have p- type carriers and the carrier type is not changed during annealing, but the electrical resistivity increases with annealing temperature. Magnetization characteristics show that the as- grown amorphous Ge1-xMnx thin films are ferromagnetic and the Curie temperatures are around 130 K. Curie temperature and saturation magnetization of annealed Ge1-xMnx thin films increase with annealing temperature. Magnetization behavior and X- ray analysis implies that formation of ferromagnetic Ge3Mn5 phase causes the change of magnetic and electrical properties of annealed Ge1-xMnx thin films.