Mechanistic studies of the thermal decomposition of metal carbonyls on Ni(100) surfaces in connection with chemical vapor deposition processes

Abstract

The thermal decomposition of Fe(CO)5, Cr(CO)6, Mo(CO)6, and W(CO)6 on Ni(100) surfaces and under ultrahigh vacuum conditions was studied by using temperature programmed desorption and x-ray photoelectron spectroscopies. The initial adsorption of those metal carbonyls is mostly molecular at low temperatures, but complete decarbonylation to the naked metal takes place in all cases upon thermal activation. Experiments with coadsorbed isotopically labeled 13CO provided indirect evidence for a stepwise mechanism for Fe(CO)5 which may include the formation of tetra- and tricarbonyl intermediates on the surface. For Cr(CO)6, Mo(CO)6, and W(CO)6, on the other hand, complete decomposition occurs in a narrow range of temperature, and no intermediate could be isolated on the surface. The deposition of metal films via metal carbonyl activation was studied under steady state conditions as well. Continuous deposition was seen at substrate temperatures as low as 300 K, but the grown films were found to incorporate both carbon and oxygen under most conditions tested and to change their morphology depending on the substrate temperature during deposition.

The interaction of size-selected Ru3 clusters with RF-deposited TiO2: probing Ru–CO binding sites with CO-temperature programmed desorption

“…SiO 2 ) and others such as zeolites. 19,[24][25][26][27][28][29] When depositing ligand-stabilized clutters, extra post-deposition surface treatments such as heating are needed to remove the ligands if bare metal clusters are desired on the substrate. TiO 2 is a photocatalytically active substrate 30 and is a common choice as a substrate for the deposition of clusters.…”

The Importance of Decarbonylation Mechanisms in the Atomic Layer Deposition of High‐Quality Ru Films by Zero‐Oxidation State Ru(DMBD)(CO)3

“…More generally, zero-oxidation state precursors have been reported to chemisorb to the surface through a thermally induced, surfacemediated dissociation or dissociative substitution reaction, facilitating rapid nucleation. [35][36][37][38][39] Although this pathway can reduce the self-limiting nature of their reaction with the surface and make them more challenging to apply to ALD, such precursors have been widely used in the CVD literature. [40][41][42] While there are many factors that affect nucleation and growth, the reported correlation between oxidation state and nucleation delay raises questions about the reaction mechanisms taking place.…”

Encapsulation of Size-Selected Ru3 Clusters into RF-Deposited TiO2

“…Two commonly utilised approaches for depositing Ru clusters onto substrates are firstly depositing gasphase size-selected, bare clusters using a cluster source (CS), and secondly depositing ligand-stabilised clusters such as Ru3(CO) 12. The latter can be deposited onto surfaces in two different ways: solution deposition (here shortened to SD, also called solution submersion) [18] and chemical vapor deposition (CVD) [19][20][21][22][23][24][25][26][27][28][29]. The deposition method can affect the resultant cluster properties, however very few studies have directly compared the cluster properties of identically sized clusters resulting from different deposition methods [21,30].…”