Surface properties of nanodiamond films deposited by electrophoresis on Si(100)

• Published in: Diamond and related materials 1998-09, Vol.8 (2-5), p.805-808
• Main Authors: Maillard-Schaller, E, Kuettel, O M, Diederich, L, Schlapbach, L, Zhirnov, V V, Belobrov, P I
• Format: Article
• Language: English
• ISSN: 0925-9635

The surface properties of diamond nanoparticles (40-50 A in diameter) have been investigated by X-ray photoelectron spectroscopy (XPS), UV photoelectron spectroscopy (UPS) and Raman spectroscopy. The diamond nanoparticles have been deposited on flat Si(100) substrates by electrophoresis/dielectrophoresis. The as-deposited films are strongly oxidized and present a 1-2% nitrogen content. After treatment at 850 deg C in H sub 2 plasma for 60 min, the oxygen is removed, and the position of the C 1s core- level peak indicates a n-type electronic comportment of the diamond nanoparticles. Raman spectroscopy of the as-deposited film shows a sp exp 3 contribution at 1321 cm exp -1 and a sp exp 2 contribution around 1620 cm exp -1 . The 12 cm exp -1 shift of the sp exp 3 contribution with respect to the bulk diamond peak at 1333 cm exp -1 is attributed to a phonon confinement effect due to the size of the diamond particles. The H sub 2 plasma treatment induces a size decrease of the nanocrystallites confirmed by Raman and scanning electron microscopy (SEM) measurements. UPS spectroscopy shows a negative electron affinity of -0.2 eV of the hydrogenated nanodiamond film.