Trimethyl Methylcyclopentadienyl Platinum Research Articles

Initial reaction mechanism on the atomic layer deposition of platinum on a graphene surface: A density functional theory study

The atomic layer deposition (ALD) of platinum on carbon supports has been studied extensively due to the wide potential application in microelectronics and catalysis. The initial reaction mechanism of atomic layer deposited platinum on a hydroxylated graphene surface has been investigated using density functional theory (DFT). Methylcyclopentadienyl trimethylplatinum (MeCpPtMe3) and molecular oxygen were adopted as precursors. In addition, finite temperature calculations were performed to investigate the effect of process conditions. The free energies were calculated at temperatures 200°C and 300°C with pressure of 1Pa. The results obtained from the simulations were compared and correlated with available literature.

Synthesis of Pt/SiO2 Catalyst Nanoparticles from a Continuous Aerosol Process using Novel Cyclo‐octadienylplatinum Precursors

Investigations on the metal‐organic (MO)CVD of platinum nanoparticles on spherical, chemical vapor synthesis (CVS)‐produced SiO2 substrates are discussed in this paper. Commercially available methylcyclopentadienyl trimethyl platinum (MeCpPtMe3) (1) and three newly synthesized cyclooctadienyl platinum precursors are chosen and tested during a continuous CVD/CVS process. The synthesis of this new class of stable, halogen‐free precursors for atmospheric pressure (AP)CVD is presented. The complexes [PtMe2(R‐COD)], where R = Et (2a), nBu (2b), and iBu (2c), are shown to be highly suitable for the preparation of platinum nanoparticles. The precursors are characterized and their thermal properties are studied by thermogravimetric analysis (TGA) and infrared (IR). Investigations of the precursor decomposition mechanism, the effect of oxygen, and the autocatalytic effect during CVD are also carried out. Finally, transmission electron microscopy (TEM) and X‐ray photoelectron spectroscopy (XPS) analyses prove that continuous CVS of gas‐borne support particles combined with MOCVD of these newly synthesized platinum precursors gives ordered, defined platinum nanocatalysts with high dispersion and narrow size distribution (2 − 3 nm).

Physisorption of an organometallic platinum complex on silica: an ab initio study

The interaction of trimethyl methylcyclopentadienyl platinum (MeCpPtMe3) with a fully hydroxylated SiO2 surface has been explored by means of ab initio calculations. A large slab model (3 × 3 × 4 supercell) cut out from the hydroxylated β-cristobalite SiO2 (111) surface was chosen to simulate a silica surface. Density functional theory calculations were performed to evaluate the energies of MeCpPtMe3 adsorption to the SiO2 surface. Our results show that the physisorption of the molecule is dependent on both (i) the orientation of the adsorbate and (ii) the adsorption site on the substrate. The most stable configuration was found with the MeCp and Me3 groups of the molecule oriented toward the surface. Finally, we observe that van der Waals corrections are crucial for the stabilization of the molecule on the surface. We discuss the relevance of our results for the growth of Pt-based nanostructured materials via deposition processes such as electron beam-induced deposition.

A Tunable Strain Sensor Using Nanogranular Metals

This paper introduces a new methodology for the fabrication of strain-sensor elements for MEMS and NEMS applications based on the tunneling effect in nano-granular metals. The strain-sensor elements are prepared by the maskless lithography technique of focused electron-beam-induced deposition (FEBID) employing the precursor trimethylmethylcyclopentadienyl platinum [MeCpPt(Me)3]. We use a cantilever-based deflection technique to determine the sensitivity (gauge factor) of the sensor element. We find that its sensitivity depends on the electrical conductivity and can be continuously tuned, either by the thickness of the deposit or by electron-beam irradiation leading to a distinct maximum in the sensitivity. This maximum finds a theoretical rationale in recent advances in the understanding of electronic charge transport in nano-granular metals.

Direct-write patterning of microstructured porous silicon arrays by focused-ion-beam Pt deposition and metal-assisted electroless etching

Photoluminescent porous silicon (PSi) patterns of micrometer dimension were produced by the Pt-assisted electroless etching of Si in 1:1:2 methanol:HF:H2O2. Pt-containing squares with side lengths ranging from 1.25to20μm were defined by a focused-ion-beam-assisted maskless deposition of Pt from an organometallic precursor, trimethylmethylcyclopentadienyl platinum. The Pt-patterned Si samples were then etched to produce photoluminescent pixel arrays with high fidelity transfer of the Pt deposition pattern into luminescent pixels of varying size. The morphology of the PSi patterns was correlated with the spatial luminescence characteristics at the individual pixel level. Luminescent pixels with feature sizes down to ca. 1μm were largely confined to the areas initially coated with Pt, and the morphologies produced within any one set of equal-sized Pt squares were similar. For 5-μm pads and larger, the morphologies obtained were an admixture of a porous structure coexisting with deeper heavily etched crater regions. Only the porous areas were observed to emit, with the deeper crater areas being dark in a two-photon luminescence. The smaller 1.25- and 2.5-μm pads exhibited a common morphology, in which a brightly luminescent outer ring surrounds a weaker but still distinguishable luminescence in the center of the etched structure. These results are in contrast with the spatial luminescence patterns and morphologies for the millimeter-scale Pt pads [S. Chattopadhyay, X. Li, and P. W. Bohn, J. Appl. Phys. 91, 6134 (2002)], in which electroless etching and, thus, PSi formation is observed in the regions not initially coated with Pt.

MOCVD of Platinum Films from (CH3)3CH3CpPt and Pt(acac)2: Nanostructure, Conformality, and Electrical Resistivity

AbstractA potentially manufacturable liquid‐source MOCVD process was applied to deposit platinum (Pt) films (12–140 nm) on thermally oxidized Si substrates. The deposition of Pt films was carried out at a substrate temperature of 350 °C by oxygen‐assisted pyrolysis of complex precursors in a low‐pressure, hot‐wall reactor. The effects of two different metal–organic precursors, a) trimethyl methyl cyclopentadienyl platinum [(CH3)3CH3CpPt], and b) platinum acetylacetonate [Pt(acac)2], on the properties of Pt films were studied. Although the polycrystalline Pt films deposited from Pt(acac)2 exhibited a preferred (111) orientation with a X‐ray intensity ratio of I(111)/I(200) = 40, the films deposited from (CH3)3CH3CpPt were highly (111) oriented with I(111)/I(200) = 270. The following properties were typical of Pt films from Pt(acac)2 as compared to Pt films from (CH3)3CH3CpPt: finer grain size (25 nm vs. 50 nm), smaller root mean square (rms) surface roughness (5 nm vs. 15 nm), and better step coverage (95 % vs. 35 %). These experimental findings indicated that growth of Pt films from Pt(acac)2 occurred under the kinetically‐limited regime, whereas the deposition of Pt from (CH3)3CH3CpPt was limited by the mass transport rate. Additionally, the temperature (4.2–293 K) dependence of the electrical resistivities (ρ) of Pt films was measured and the electron mean free paths were estimated. It was observed that ρ(T) deviated from Matthiessen's rule.

Fabrication of Nano Electron Source Using Beam-Assisted Process

A new structure and the fabrication processes of a field emission electron source using chemical reactions by an electron beam (EB) or a focused ion beam (FIB) were proposed. Various gate diameters and emitter heights can freely be fabricated using these processes. An insulator of ring shape was deposited on a Si substrate by chemical reactions using EB or FIB in a tetraethyl orthosilicate (TEOS) atmosphere. A Pt gate was then deposited on the insulator ring using EB in a methyl cyclopentadienyl trimethyl platinum [C5H5Pt(CH3)3] atmosphere. A Pt emitter was deposited into the ring gate opening in the same way. In the quickest process, an electron-source structure with a gate diameter of 300 nm and a cathode height of 500 nm could be fabricated in 189 s using only an EB-induced reaction.

Characterization of platinum films deposited by focused ion beam-assisted chemical vapor deposition

This work presents results from the characterization of ion-assisted chemical vapor deposition of platinum from trimethyl–methylcyclopentadienyl–platinum (C9H16Pt). Films were deposited in squares ranging from 50 to 200 μm on a side using a focused ion beam system. The effects of Ga+ ion flux and precursor flux on the deposited films’ composition and resistivity were determined. Films were characterized using atomic force microscopy, Rutherford backscattering spectrometry, and Auger electron spectroscopy. Results show that increasing precursor flux at constant ion flux increases Pt and C, but decreases Ga content of the film. Increasing ion flux at constant precursor flux increases Pt content, while decreasing C content of the films. Resistivity did not depend on the thickness of 50–200 nm thick films. Resistivity was shown to follow C content, with films with lower C content having lower resistivity.

Properties of Platinum Films by Liquid-Source MOCVD in H 2 and O 2

A preliminary evaluation of Pt films, deposited at rates of 0.4-7 nm/min by a potentially manufacturable liquid-source MOCVD technique, was carried out with respect to microstructure, step coverage, and electrical properties. The Pt films (12-140 nm) were deposited on various substrates (thermal-SiO 2 /Si, native-oxide/Si, TiN/SiO 2 /Si) via the pyrolysis of trimethyl methyl cyclopentadienyl platinum [(CH 3 ) 3 CH 3 CpPt]. The substrate temperature regimes through which Pt deposition occurred, were 175-250°C and 300-450°C in H 2 and O 2 ambient, respectively. The growth mechanisms of the Pt films, deposited under H 2 and O 2 ambient, were inferred from the observed growth rate, texture evolution, grain size, and estimated nucleation density. Additionally, the step-coverage of Pt deposited on TiN at T sub of 375°C in O 2 was 80%. Moreover, the resistivity of a 30 nm Pt film was 22.8 w z -cm.

Novel high resolution scanning thermal probe

Scanning thermal microscopy is a scanning proximal probe technique, which can be used for mapping spatial variation of thermal properties of a surface such as temperature, thermal conductivity, and thermal diffusivity. The sensor presented here is a resistance based probe consisting of a nanometer-sized filament formed at the end of a piezoresistive atomic force microscope type cantilever. The freestanding filament is deposited by focused electron beam deposition using methylcyclopentadienyl trimethyl platinum as a precursor gas. The filament height is in the range of 2–5 μm, with typical “wire” diameters between 30 and 100 nm. Typical deposition times are between 2 and 5 min, and might be further shortened by optimizing the precursor gas flux. Because of its small size, the new probe has a high spatial resolution (<20 nm tip end radius) and, due to the low thermal mass, a high thermal sensitivity and fast response time. In this article, experiments designed to characterize the mechanical stability and electrical and thermal properties of the nanometer-sized probe are presented.