GROWTH AND CHARACTERIZATION OF MAGNETIC METAL MN FILM BY MOCVD

Metal manganese films have successfully been grown on (100) and (111) GaAs substrates by metal organic chemical vapour deposition using tric arbonyl (methylcyclopentadienyl) manganese (TCMn) as the Mn source mat erial. The onset of diffusion limited growth occurs at a temperature o f similar to 470 degrees C. Above this transition temperature, the gro wth is relatively independent of the temperature and limited only by t he rate at which the precursor is able to diffuse to the substrate. At the low temperatures, the growth rate is limited by the pyrolysis beh aviour of the TCMn and is thermally activated with an activation energ y of similar to 220 kJ mol(-1). This compares with the activation ener gy obtained for the decomposition of the TCMn of 236 kJ mol(-1). The g rowth characteristic of Mn films has also shown that no growth took pl ace below the temperature of 410 degrees C and the morphology of the l ayers grown at the higher temperature of 470 degrees C was considerabl y better than that of the layers grown at lower temperatures. Ex-situ reflection high-energy electron diffraction (RHEED) showed the films t o be polycrystalline Mn, with good surface morphology. Surface roughne ss was measured to be similar to 4 nm and was probably limited by oxid ation, when exposed to air.