Highlights
- Highlights
- Position gold nanoparticles with DNA origami nanostructures
- Porous organosilicate films
- Nanoporous Carbon Supercapacitors
- Self-Assembly of the Cephalopod Protein Reflectin
- Low T route towards hybrid solar cells
- Ion tracks formation on surfaces
- Magnetic mesoporous assemblies
- Heavy Ion Irradiation of GaN
- Additives for Organic Photovoltaics
- Hybrid Solar Cells: Influence of Molecular Precursor
- 2-Step Perovskite Conversion
- Organic solar cells by in-operando GISAXS
- Nanoimprinted comb structures
- Nanomaterial coatings
- Zeolite nanoclusters
- Magnetron sputtered W films
- Anisotropic Ge QD lattices
- Control of lipid structuring
- Highly Luminescent Frameworks
- Fluid Bilayers
- Mesoporous carbons
- Preparation of ZnO particles
- Structural Characterization of MOF-5 crystals
- Evolution of protein coronas
- Nanochannels for nanofluidics
- Ordered Ge nanoclusters in amorphous matrix
- Anaesthesia
- Tutte le pagine
Structure and morphology of magnetron sputtered W films
|
The structural and morphological details of magnetron sputtered tungsten (W) thin films as a function of the Ar working gas pressure and the sputtering power are presented. The crystal structure of the W films was examined with grazing incidence x-ray diffraction (GIXRD), while the morphology characterization was performed by x-ray reflectivity (XRR) and grazing incidence small-angle x-ray scattering (GISAXS). W films have an important role in a number of technological applications, including e.g. optic and near-infrared transition edge sensors, diffusion barriers in semiconductor interconnect layers, absorption masks in x-ray lithography or diffracting layers in x-ray mirrors. Recently, W films have also been used as coatings of plasma-facing surfaces in tokamaks. All these studies reported that the W film structure and morphology are crucial for the final properties of the device or functionality of the coating.
Tungsten thin films exhibit two crystalline modifications: a thermodynamically stable body centred cubic (bcc) phase (α-W) and a metastable A15 phase (β-W). These two phases exhibit different properties. The lattice parameters of α-W and β-W are 3.16Å and 5.04 Å, respectively. The electrical resistivity of α-W is always lower than the electrical resistivity of β-W. The superconducting transition temperatures of the two phases are 15mK for α-W and between 1 and 4K for β-W. Moreover, the hardness of α-W and β-W films is different. The occurrence and stability of β-W in physical vapour deposition (PVD)-produced thin films are associated with the presence of oxygen in the deposition chamber, either as a controlled admixture or as a residual gas. Beyond the conditions for β-W formation, an amorphous tungsten film is formed.
|
We find that the crystalline properties and nanoporosity vary systematically with the deposition conditions. Depositions at low Ar pressures (<5mTorr) and high powers (>40 W) result in compact and smooth layers with only α-W crystallites. By reducing the sputtering power (20 W), along with stable α-W, a metastable β-W phase occurs. For an even lower power (10 W), the W film becomes amorphous and exhibits a columnar morphology accompanied by a 25% reduced layer’s mass density compared with that of bulk tungsten. Retrieve article
Structure and morphology of magnetron sputtered W films studied by x-ray methods; |