Управление свойствами алмазоподобных кремнийуглеродных пленок
At a Glance
Section titled “At a Glance”| Metadata | Details |
|---|---|
| Publication Date | 2020-01-01 |
| Journal | Физика твердого тела |
| Authors | А.И. Попов, А.Д. Баринов, В.М. Емец, Т.С. Чуканова, М.Л. Шупегин |
| Citations | 2 |
| Analysis | Full AI Review Included |
Executive Summary
Section titled “Executive Summary”This research demonstrates highly effective control over the electrophysical and mechanical properties of amorphous diamond-like silicon-carbon (a-SiC) films using combined structural and chemical modification techniques.
- Property Control Range: Achieved control over electrical conductivity spanning more than 16 orders of magnitude by combining structural modification and transition metal doping.
- Structural Modification: Tuning the DC substrate bias voltage (Vbias) increased nanohardness from 22 GPa to 28 GPa and reduced surface roughness from 0.9 nm to 0.35 nm.
- Chemical Modification (Doping): Introducing transition metals (Ta, W, Mo) created nanocomposites, increasing conductivity by up to 9 orders of magnitude (from 10-6 to 103 Ω-1 cm-1) via a percolation mechanism.
- Frequency Dependence: Switching the axial electric field frequency from 1.76 MHz (High Frequency) to 100 kHz (Low Frequency) significantly altered film properties, including reducing dielectric loss (tan δ) and changing the effect of Argon pressure on conductivity.
- Structural-Chemical Coupling: The study highlights that metal doping not only introduces a conductive phase (metal carbides, e.g., TaC, WC, MoC) but also structurally modifies the amorphous SiC matrix by depleting carbon atoms, which must be accounted for in predictive models.
Technical Specifications
Section titled “Technical Specifications”| Parameter | Value | Unit | Context |
|---|---|---|---|
| Nanohardness (Low Bias) | 22 | GPa | Vbias = -200 V |
| Elastic Modulus (Low Bias) | 135 | GPa | Vbias = -200 V |
| Nanohardness (High Bias) | 28 | GPa | Vbias = -400 V |
| Elastic Modulus (High Bias) | 190 | GPa | Vbias = -400 V |
| Surface Roughness (High Bias) | 0.35 | nm | Vbias = -1000 V |
| Surface Roughness (Low Bias) | 0.9 | nm | Vbias = -100 V |
| Conductivity (Undoped, No Ar) | 3 * 10-12 | Ω-1 cm-1 | 1.76 MHz field frequency |
| Conductivity (Undoped, High Ar) | 1 * 10-6 | Ω-1 cm-1 | PAr = 7 * 10-4 Torr, 1.76 MHz |
| Conductivity (Ta Doped, Max) | 103 | Ω-1 cm-1 | Ta concentration > 30 at.% (9 orders increase) |
| Metal Doping Concentration | Up to 30-35 | at.% | Transition metals (Ta, W, Mo) |
| WC Nanocrystal Size | ~1 | nm | Tungsten carbide phase |
| MoC Nanocrystal Size | 2.5 | nm | Molybdenum carbide phase |
| Thermal Cathode Temperature | ~2500 | °C | Plasma generation |
| Ceramic Disperser Temperature | 300-400 | °C | Precursor vaporization |
Key Methodologies
Section titled “Key Methodologies”The films were synthesized using plasma-chemical decomposition of organosilicon precursors in a custom cross-field discharge system (Figure 1).
- Synthesis Setup: Utilized a vacuum chamber with a thermal cathode (T ≈ 2500 °C) and a ceramic disperser (T ≈ 300-400 °C) for precursor delivery.
- Plasma Generation: Plasma was generated using crossed DC (radial) and AC (axial) fields. A magnetron was used for sputtering transition metals during chemical modification.
- Precursors: Two primary organosilicon precursors were used, differing in molecular structure:
- PPMS (Polyphenylmethylsiloxane): Asymmetric chains containing phenyl rings (higher carbon content).
- PMS (Polymethylsiloxane): Linear molecules with symmetrically arranged CH3 groups.
- Structural Modification Levers:
- Substrate Bias Voltage (Vbias): Controlled the kinetic energy of depositing particles, influencing film density and sp3 bond formation.
- Axial Field Frequency: Tested at 1.76 MHz (High Frequency) and 100 kHz (Low Frequency) to alter plasma characteristics and ion bombardment intensity.
- Argon Pressure (PAr): Controlled the intensity of Ar ion bombardment, affecting defect concentration and structural disorder.
- Chemical Modification: Transition metals (Ta, W, Mo) were introduced via the magnetron, forming metal carbide (MeC) nanocrystals within the amorphous SiC matrix, creating a percolation system.
- Characterization: Properties were analyzed using X-ray microanalysis (elemental composition), AFM (morphology), Novocontrol Alpha-A (dielectric properties), ASEC-03E (electrophysical properties), and NHT2-TTX nanoindentation (mechanical properties).
Commercial Applications
Section titled “Commercial Applications”The ability to precisely tune the mechanical and electrical properties of these diamond-like silicon-carbon films makes them highly valuable for advanced engineering applications:
- Protective and Antifriction Coatings: The high nanohardness (up to 28 GPa) and low surface roughness make these films ideal for wear-resistant coatings on mechanical components (e.g., bearings, gears).
- Micro/Nanoelectronics: The massive tunability of conductivity (10-12 to 103 Ω-1 cm-1) allows the material to function as:
- High-performance Dielectrics: Films synthesized at 100 kHz with low Ar pressure show reduced dielectric loss (low tan δ).
- Tunable Resistors/Interconnects: Metal-doped films can be engineered to be highly conductive, suitable for contacts or conductive pathways in integrated circuits.
- MEMS/NEMS Devices: Used as robust, wear-resistant layers in micro- and nano-electromechanical systems where durability and low friction are critical.
- Optoelectronics: As the films are derived from amorphous carbon materials, they may be suitable for applications requiring specific bandgap or localized state control.
View Original Abstract
The possibilities of controlling the electrophysical and mechanical properties of amorphous diamond-like silicon-carbon films by the methods of structural, chemical and structural-chemical modification are considered. The factors of the structural modification were the bias voltage and its frequency during the synthesis of films, the argon pressure in the vacuum chamber, and precursors with different molecular structures. For chemical and structural-chemical modification, transition metals were introduced into the film with a concentration of up to 30 - 35 at. % The high efficiency of controlling the physical properties of the films by the considered methods is shown.