An Influence of the Si(111)3-4° Vicinal Surface on the Solid Phase Epitaxy of α-Fesi_2 Nanorods and their Crystal Parameters

摘要

The morphology and structure of iron silicide nanorods formed on Si(l 11) vicinal surface by the SPE method at T = 630 °C were studied. Optimal Fe coverage and Fe deposition rate for the formation of a dense array of the nanorods (54-65% of the substrate area) on Si (111) surface with 3-4° miscut angles were established. The aspect ratio of the nanorods is 1.9-3.3. Cross-sectional images of a high-resolution transmission electron microscopy (HRTEM) have shown that the nanorods have α-FeSi_2 crystal structure. They are strained along the "a" axis and stretched along the "c" axis, which increased the unit cell volume by 10.3%. According to HRTEM image analysis, the nanorods have the following epitaxial relationships: α-FeSi_2[02l]//Si[ll0] and α-FeSi_2(112)//Si(111). All the data obtained have provided, for the first time, a direct evidence of α-FeSi_2 nanorods formation on Si(111) vicinal surface without noticeable penetration of Fe atoms into the Si substrate.