Microstructure, phase transition, and interfacial chemistry of Gd2O3/Si(111) grown by electron-beam physical vapor deposition

作者：Weng Xiaojun^*; Grave Daniel A; Hughes Zachary R; Wolfe Douglas E; Robinson Joshua A

来源：Journal of Vacuum Science and Technology A, 2012, 30(4): 041512.

DOI：10.1116/1.4726266

The effects of growth temperature, film thickness, and oxygen flux on the microstructure, phase transition, and interfacial chemistry of gadolinium oxide (Gd2O3) films grown on Si(111) substrates by electron-beam physical vapor deposition were investigated using a combination of transmission electron microscopy (TEM), electron diffraction, scanning TEM, x-ray energy dispersive spectrometry, and electron energy loss spectrometry. The authors find that a low growth temperature (250 degrees C) and a high oxygen flux (200 sccm) led to a small grain size and a high porosity of the Gd2O3 film. Lowering the oxygen flux to 50 sccm led to reduced film porosity, presumably due to the increased diffusion length of the Gd atoms on the surface. Increasing the growth temperature to 650 degrees C resulted in a film with large columnar grains and elongated pores at the grain boundaries. Thin films grown at 250 degrees C consisted of cubic Gd2O3, but thermodynamically less stable monoclinic phase formed as the film thickness increased. Lowering the oxygen flux apparently further promoted the formation of the monoclinic phase. Furthermore, monoclinic phase dominated in the films grown at 650 degrees C. Such phase transitions may be related to the stress evolution of the films at different temperatures, thicknesses, and oxygen fluxes. Enhanced Gd2O3/Si interfacial reaction was observed as the growth temperature, film thickness, and oxygen flux increased. Moreover, oxygen was found to play a crucial role in the Gd2O3/Si interfacial reaction and the formation of Gd-Si-O interface layers, which proceeded by the reaction of excess oxygen with Si followed by the intermixing of SiOx and Gd2O3.

• 出版日期2012-7