Interdiffusion processes at irradiated Cr/Si interfaces

Chromium silicon CrSi alloys are foreseen as possible materials for spintronic devices. Ion beam mixing could be an efficient technique to produce thin films of such alloys at room temperature while avoiding thermal diffusion. In order to assess this point, we have irradiated 20 nm Cr layer on a (100) Si wafer with 70 keV Kr ions. The X-ray reflectometry technique combined with Transmission Electron Microscopy and Energy Dispersive X-ray analysis was applied to analyze, at the nanometric scale, the formation of Cr/Si blurred interfaces induced by ion beam mixing. From the analysis of reflectivity curves, it appears that nanometric Cr5Si3 and CrSi2 phases are produced at the early stage of the process. The existence of these two paramagnetic phases gives some clues to explain the reason why the experimentally observed ferrimagnetism was weaker than predicted. (C) 2014 Elsevier B.V. All rights reserved.