Transmission electron microscope structural study of Y₂O₃ films grown on Si(111) substrates by ultrahigh vacuum ionized cluster beam

Y₂O₃ films were grown on SiO₂-covered Si(111), and hydrogen-terminated Si(111) substrates at a temperature of 500°C by ultra-high vacuum ionized cluster beam deposition. The microstructures and growth behavior of these films have been investigated by transmission electron diffraction (TED) and high resolution transmission electron microscopy (HREM). The TED results show that the Y₂O₃ grown on the SiO₂-Si has the epitaxial relationship of (11-1)_Y(2)O(3)//(111)_Si and [-110]_Y(2)O(3)//[-110]_Si. The film on the H-Si contains YSi_2-x and amorphous YSi_xO_y layers at the interface, having the orientation relationship each other. For the YSi_2-x and the Si substrate, the relationship is (0001)YSi_2-x//(111)Si and [1-210]YSi_2-x//[-110]Si. For the Y₂O₃ and the YSi_2-x, the relationship is as follows: (11-1)Y₂O₃//(0001)YSi_2-x and [-110]Y₂O₃//[1-210]YSi_2-x; (111)Y₂O₃//(0001)YSi_2-x and [-110]Y₂O₃//[1-210]YSi_2-x. The formation mechanism of the interfacial phases of SiO_x, YSi_xO_y, and YSi_2-x are described. It is shown that the crystallinity of the Y₂O₃ film on the SiO₂-Si(111) is better than that of Y₂O₃ on H-Si(111).