Atomic Layer Deposition of Iron Oxide Thin Films and Nanotubes using Ferrocene and Oxygen as Precursors

Abstract

Thin films and nanotubes of iron oxide are deposited using atomic layer deposition (ALD) on Si(100) and anodic aluminum oxide (AAO), respectively. Ferrocene, Fe(Cp) 2 , and oxygen are used as precursors. Successful depositions are carried out in the temperature range 350-500 -C on Si(100), while all depositions on AAO are made at 400 -C. The growth per cycle values are around 0.14 nm on Si(100) in the temperature range 350-500 -C and 0.06 nm on AAO. Below 500 -C, the iron oxide crystallizes as a phase mixture on both types of substrates. One of the phases is identified as the rhombohedral Fe 2 O 3 phase (hematite), but the second phase cannot be unambiguously identified. Above 500 -C, only phase pure hematite is detected. For deposition of nanotubes, in-house made AAO membranes are used, having an aspect ratio of 30. By etching of the AAO membranes after deposition, free-standing nanotubes retaining the order of the AAO template can be fabricated.

Atomic layer deposition for aligned growth of and conformal deposition onto double and triple walled carbon nanotubes

“…This layer was deposited using RF magentron sputtering from an Al 2 O 3 target (plasmaterials) or by ALD using TMA and H 2 O precursors. This step was followed by ALD deposition of Fe 2 O 3 using ferrocene and O 2 precursors [6,7]. The ALD films were fabricated by alternating the entrainment of the reactant precursors into the N 2 carrier gas.…”

Stoichiometry of Nickel Oxide Films Prepared by ALD

“…[3] Metallocenes or their derivatives can be either hydrolyzed or oxidized in ALD mode (depending on their reactivity) to obtain various oxides MO or M 2 O 3 , M = Mg, Sr, Ba, Sc, Y, Zr, Fe, Ru, Co, Ni, Pt, Lu. [4][5][6][7] In the hydrolytic case 25 the electropositive element retains its initial oxidation state n from the Cp n M compound, whereas in an oxide obtained by oxidation of Cp n M the oxidation state of M may be higher than n. In the case of the ALD reaction between nickelocene and ozone (O 3 ), the stoichiometry of the product material has 30 not been investigated to date, under the assumption that nickel(II) oxide, NiO, should be formed. [7,8] This assumption is credible in NiO films formed from a hydrolysis reaction, [9] but much more questionable when the aggressive oxidant ozone is involved, especially since sub-stoichiometric oxides 35 are well documented.…”

Atomic Layer Deposition-incorporated Catalyst Deposition for the Vertical Integration of Carbon Nanotubes

“…Fe(Cp) 2 was chosen as the precursor for the ALD. The ALD process was carried out based on a previous study [7] where the vertical pores of an AAO layer were filled with Fe oxide by ALD. Fe(Cp) 2 and oxygen were alternately supplied to an ALD reactor chamber, into which the AAO was placed in order to produce a Fe-oxide layer on the surface of the AAO template.…”