Growth and structure of Fe on MgO(001) studied by modulated electron emission

Fe films 10 monolayers thick were prepared in ultrahigh vacuum by thermal deposition on in-air cleaved MgO(0 0 1) substrate held at room temperature and 500 degreesC. Auger electron spectroscopy, low energy electron diffraction, and scattering-interference of primary and backscattered electrons were used to investigate the growth mode and the structure of the film. The room temperature deposition results in a nearly continuous (90% fractional coverage) body-centred-tetragonal film with the Fe[001]parallel toMgO[001] and Fe<100>parallel toMgO<110> orientation relationships. Film annealing at 300 degreesC increases the quality of the film. In-plane expansion of +2.4% and out-of-plane contraction of - 3.2% of the Fe cubic cell has been determined. A complete removal of the tetragonal distortion and a strong islanding (35% fractional coverage) occur for annealing temperature of 500 degreesC. Film deposition at 500 degreesC substrate temperature leads to body centred Fe islands that cover about 55% of the substrate. (C) 2001 Elsevier Science B.V. All rights reserved.