Interfacial layer formation during the growth of Gd2O3 on Si(001) and its thermal stability

The thermal stability of monoclinic Gd2O3 grown on Si(001) as well as changes of the interfacial layer formed during the growth are investigated during rapid thermal annealing in nitrogen atmosphere between 600 degrees C and 1000 degrees C using x-ray diffraction and transmission electron microscopy (TEM). The monoclinic Gd2O3 layer was grown at 400 degrees C and oxygen partial pressure of 5 x 10(-7) mbar. The Gd2O3 layers exhibit first an initial strain release during annealing at 800 degrees C and subsequent induced thermal strain after annealing at 1000 degrees C. Thereby, the monoclinic structure remained unchanged. The interfacial layer formation during the growth is discussed in the framework of different physical effects, such as the presence of a nucleation barrier or the presence of a partially oxidized surface. The interfacial layer thickness increases with increasing annealing temperature, which can be attributed to the presence of oxygen and the high diffusivity during the annealing. The TEM investigations show a change in the layer contrast, which indicates a change in the interfacial layer composition. This could be due to the accumulation of oxygen and a subsequent release at higher temperatures.