Microwave enhanced CVD

Microwave enhanced CVD - AsTex S1500 (customized)

Daniele M. Trucchi - daniele.trucchi@ism.cnr.it

DiaTHEMA Lab:DepositionLab

Rome - Monterotondo

Customized starting from the Astex S1500 deposition system, it is a setup for the growth of polycrystalline diamond and diamondlike-carbon (DLC) layers by means of a CVD microwave plasma-assisted (MWCVD) technique. Equipped with a graphite disk that allows the heating of the samples up to 950 ° C. The technique is also used to induce hydrogen surface termination.

Methane (CH₄), which is often used as precursor for diamond growth in CVD techniques, undergoes a dissociation while exposed to a high-energy microwave plasma. Furthermore, in the process of diamond deposition the presence of hydrogen is fundamental as it prevents the formation of carbon phases with diamonds, providing a condition of thermodynamic super-equilibrium. The system also allows the growth of nitrogen doped n-type diamond using a CH₄/N₂/H₂plasma.

The MW-CVD technique is commonly used when the growing film requires the highest purity and lowest concentration of defects. The uniformity of the film thickness is limited compared to the HF-CVD technique.

TECHNICAL SPECIFICATIONS

Base pressure < 10-⁸mbar;
Microwave generator (2.45 GHz) up to 2 kW (MKS Instruments TM025 51);
3 gas lines (H, CH₄, N₂);
maximum temperature 950 °C;
partial pressures up to 100 mbar;
- by changing the partial pressure and the precursors/hydrogen ratio it's possible to obtain growth rates up to 1.5 um/hr;
3 flowmeters for H₂ (300 sccm), Ar (50 sccm) e CH₄ (10 sccm).

AVAILABLE TECHNIQUES

Substrate temperature measurement through double color IR pyrometer.

SAMPLES

Maximum active deposition area: 4 inches diameter with uniformity up to 2 inches in diameter;
Ability to insert multiple monocrystalline and polycrystalline samples.

USED FOR

deposition of poly and nano-crystalline diamond;
deposition by homo-epitaxial growth on mono-crystalline diamond;
deposition of DLC;
surface termination in hydrogen of semiconductors.

ESEMPI APPLICATIVI

Solar Thermionic-Thermoelectric Generator (ST2G): concept, material and prototype demonstration

Nitrogen-doped nanodiamond films were deposited on HfC to operate as efficient thermionic emitters in the prototype of the ST2G thermoelectric-thermoelectric solar generator.

See: D. M. Trucchi, A. Bellucci, M. Girolami, P. Calvani, E. Cappelli, S. Orlando, R. Polini, L. Silvestroni, D. Sciti, A. Kribus, Advanced Energy Materials 8, 32 (2018) 1802310
doi: 10.1002/aenm.201802310

Microwave enhanced CVD