Evolution of thin protecting Si-layer on Mn0.5Si0.5 layer at low temperatures

Evolution of 2-nm-thick protecting Si-layer on amorphous Mn0.5Si0.5 films at elevated temperatures was investigated by using conductive atom force microscopy (CAFM) and other structure and composition characterization methods. At a temperature of 300 °C, a dramatic change was observed in surface morphology with many islands forming on the surface. Those islands were SiO2 islands rather than Si ones. Further studies showed that those islands formed via first oxidation of the Si cap layer followed by the agglomeration of this SiO2 layer. Because Si cap layer has widely been used as protecting materials to prevent the surface from oxidizing and contamination, this study provides an insight on the effectiveness of thin protecting Si-layer at low temperatures.