Preparation of the subnanometer thick epitaxial Al2O3(0001) layers on Fe(110) for magnetic tunnel junctions

Growth as well as crystallographic and electronic properties of thin AlO_x layers on Fe(110) were studied by means of low-energy electron diffraction and Auger-electron spectroscopy. Al layers of different thickness were deposited on Fe(110) and successfully oxidized to AlO_x. The step-by-step oxidation of thin Al layers at room temperature leads to the formation of amorphous AlO_x on top of the Fe(110) surface. A subsequent annealing at 250 °C of the oxidized 7-Å thick Al layer results in the formation of a well-ordered Al₂O₃(0001) layer on the Fe(110) surface.