Growth Kinetics, Composition, and Morphology of Co₃O₄ Thin Films Prepared by Pulsed Liquid‐Injection MOCVD

Abstract

Cobalt oxide films were grown by pulsed liquid injection MOCVD using Co(thd) 2 dissolved in monoglyme as the precursor. The structure, morphology, and growth rate of the layers deposited on silicon substrates were studied as a function of solution concentration, deposition temperature, and oxygen partial pressure. X-ray diffraction (XRD) of films deposited from 350 C to 540 C showed a pure Co 3 O 4 spinel structure and no CoO was detected, even at the lowest oxygen pressure. X-ray photoelectron spectroscopy (XPS) was used to study the surface composition and oxidation states. Surprisingly, XPS spectra recorded for most of the films seemed to correspond to CoO. This unexpected oxidation state on the surface was assigned to the effect of the high density of edges and corners present in the surface morphology.

Remote Plasma Atomic Layer Deposition of Co3O4 Thin Films

“…14,17 Interestingly, this reveals that the surface roughness is not significantly influenced by conditions such as substrate temperature and film thickness. The electrical resistivity at room temperature was measured by FPP and found to vary between 0.5 and 5.3 XÁcm for all deposited Co 3 O 4 showing no clear trend with temperature or thickness.…”

“…4 ) is the most stable phase in the Co-O system and adopts a spinel-type cubic structure, unlike the high temperature phase CoO, which crystallizes in a cubic rock salt structure. 5 Previously Co 3 O 4 has been deposited by radio frequency magnetron sputtering, 6 sol-gel processing, 7,8 electron beam evaporation, 9 spray pyrolysis, 10 pulsed laser deposition, 11 (metal organic) chemical vapor deposition (CVD), 2,[12][13][14][15][16] and atomic layer deposition (ALD). 5,17,18 All these methods can produce high purity Co 3 O 4 .…”

Synthesis of Co3O4 nanoparticles by oxidation-reduction method and its magnetic characterization

“…Co 3 O 4 is an important magnetic p-type semiconductor, which belongs to the normal spinel crystal structure based on a cubic close packing array of oxide ions, in which Co(II) ions occupy the tetrahedral 8a sites and Co(III) ions occupy the octahedral 16d sites [15]. Extensive work has been done on preparation of Co 3 O 4 nanoparticles, including sol-gel [16,17], reduction/oxidation route [18], thermal decomposition [19,20], metal organic chemical vapor deposition (MOCVD) [21][22][23], chemical spray pyrolysis [24,25] etc. Previously, Co 3 O 4 nanoparticles with various morphologies have been synthesized [26,27].…”

A Study on the Development of CVD Precursors VI-Thermal Properties of Co(III) β-Diketonates

“…Many cobalt (II) and (III) compounds such as salts (CoI 2 , Co(OCO-CH3)2, Co(NO3)3) and complexes (Co2(CO)8, Cp2Co and related derivatives) have been utilized but no successful results have been obtained. 4 Well-known Co β-diketonates such as Co(acac)2, Co(acac)3 (acac = 2,4-pentanedionate) and Co(tmhd)2 (tmhd = 2,2,6,6-tetramethyl-3,5-heptanedionate) 6 had been used as CVD/ALD precursors but they suffers some drawbacks such as oligomeric nature 7 and limited shelf life. 4 Co(tmhd)2 and ozone have been successfully utilized to grow thin films of Co3O4 [5(c)] or epitaxial growth of cobalt oxide by ALD.…”