Phase transformations in the Mn-Ge system and in Ge x Mn1-x diluted semiconductors

Results of an X-ray diffraction study as well as magnetic and electrical measurements of the solid-state reactions in Ge/Mn polycrystalline films of an 80/20 atomic composition have been presented. It has been shown that the ferromagnetic Mn5Ge3 phase is formed first on the Ge/Mn interface after annealing at similar to 120A degrees C. The further increase in the annealing temperature to 300A degrees C leads to the beginning of the synthesis of the Mn11Ge8 phase, which becomes dominating at 400A degrees C. The existence of new structural transitions in the Mn-Ge system in the region of similar to 120 and similar to 300A degrees C has been predicted on the basis of the presented results and results obtained earlier when studying solid-state reactions in different film structures. The supposition about the general chemical mechanisms of the synthesis of the Mn5Ge3 and Mn11Ge8 phases during the solid-state reactions in the Ge/Mn films of the 80/20 atomic composition and the phase separation in Ge (x) Mn1 - x (x > 0.95) diluted semiconductors has been substantiated.