A liquid metal arc plasma source for the high-rate deposition of wide bandgap semiconductor films

• Applicants: Professor Dr. André Anders; Dmitry Kalanov, Ph.D.
• Subject Area: Synthesis and Properties of Functional Materials
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 562781822

Cathodic arc plasmas are known for providing high fluxes of ions with high kinetic and potential energies, resulting in high-rate deposition of dense and adherent thin films. The crystalline quality of the films can also be enhanced through the transfer of the ion energy – in particular, when the ion energies lie in the range between 10 and 30 eV. However, conventional arc deposition with a solid cathode involves the formation of so-called “macroparticles” (microdroplets) and their incorporation into the growing surface. This makes conventional cathodic arc plasma sources unsuitable for the growth of semiconductor materials, which require epitaxial films of high crystalline quality without defects. The aim of this project is to design, build and test a novel liquid metal arc plasma source for high-rate deposition of crystalline, high-quality wide bandgap gallium oxide thin films suitable for semiconductor devices. To overcome the disadvantages and make use of the advantages of conventional arc plasma deposition, a new plasma source will be designed in this project with the following main aspects: (i) Eliminating the macroparticles by using liquid Ga as a cathode material and a macroparticle filtering system at a moderately elevated temperature. (ii) Aiming for the desired range of Ga ion kinetic energies between 10 and 30 eV to promote surface diffusion while minimizing the damage to the lattice of the growing film. (iii) Preserving the high deposition rate to ensure low contamination from the residual gas, which is a requirement for semiconductor materials. The proposed arc source can be used as a tool in future research on high-rate, energetic, non-equilibrium deposition of high-quality semiconductor thin film materials of different low-melting point metals, such as Ga, Sn, In, Zn and their alloys. Moreover, the proposed arc source may offer a potential ecologically sustainable and energy-efficient alternative to existing high-rate deposition methods like metal-organic vapor phase epitaxy (MOVPE) and halide vapor phase epitaxy (HPVE) because it avoids hazardous and costly precursors such as pyrophoric triethylgallium (TEGa, Ga(C2H5)3) as metal-organic precursor.

• DFG Programme: New Instrumentation for Research