Highly Conductive Nanocrystalline Diamond Films and Electronic Metallization Scheme

• Published in: Materials Vol. 14; no. 16; p. 4484
• Main Authors: Chen, Xin, Mohr, Markus, Brühne, Kai, Fecht, Hans-Jörg
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 10.08.2021; MDPI
• Subjects: Affinity; Carbon; Cavitation; Chemical vapor deposition; Contact resistance; Diamond films; Electric contacts; Electrical resistivity; Electron affinity; Electrons; Gas flow; Gas mixtures; Gold; Grain boundaries; Grain size; hot-filament CVD; Metallizing; Morphology; nanocrystalline diamond; Nanocrystals; Oxygen ions; Plasma etching; Reactive ion etching; Resistance factors; Scanning electron microscopy; Sensors; Silicon substrates; Single crystals; Spectrum analysis; Wetting; X ray photoelectron spectroscopy
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma14164484

By using a methane and hydrogen process gas mixture in an appropriate hot-filament CVD process without further dopant, high electrical conductivity of over 100 S/cm has been achieved in nanocrystalline diamond films deposited on silicon single-crystalline substrates. Furthermore, it was found that an oxygen reactive-ion etching process (O-RIE) can improve the diamond film surface’s electron affinity, thus reducing the specific contact resistance. The reduction of the specific contact resistance by a factor of up to 16 was realized by the oxygen ion etching process, down to 6×10−6 Ωcm2. We provide a qualitative explanation for the mechanism behind the contact resistance reduction in terms of the electron affinity of the diamond surface. With the aid of XPS, AFM, and surface wetting measurements, we confirmed that a higher surface electron affinity is responsible for the lower specific contact resistance of the oxygen-terminated nanocrystalline diamond films.