Concepts and mechanisms of dislocation density reduction in heteroepitaxial diamond

• Applicant: Dr. Matthias Schreck
• Subject Area: Experimental Condensed Matter Physics
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 453637298

Heteroepitaxial diamond can be grown by chemical vapor deposition (CVD) on Ir/YSZ/Si in wafer size. Under appropriate process conditions, the initial dislocation density of > 10^10 cm^-2 drops to values of ~ 7×10^6 cm^-2 at thicknesses of 2 - 3 mm. For a successful application of the material in the fields of high power electronics, quantum sensing or optics a further reduction is desirable. In the present project we will explore several alternative concepts like epitaxial lateral overgrowth (ELO) using different mask materials, geometries, as well as mask-less approaches or the recently published Metal Assisted Termination (MAT) method in order to evaluate their efficiency and the underlying mechanisms of dislocation density reduction. Pseudosubstrates with defect densities of ~10^7 cm^-2 synthesized by heteroepitaxy will be applied to deposit masks, form structures or grow MAT layers before they are overgrown in a microwave plasma CVD process. Besides the simple but highly accurate etch pit counting method, characterization will include high resolution x-ray diffraction, Raman-, photoluminescence- and cathodoluminescence spectroscopy as well as transmission electron microscopy. Defect-reduced samples will be supplied to partners at accelerator facilities for the preparation of particle and radiation detectors and the analysis of their properties.

• DFG Programme: Research Grants