Morphology and Raman spectra of diamond films grown with a plasma torch

A process for diamond film deposition with an inductively coupled plasma to rch has been implemented at CSEM. Growth speeds up to 40 mu m/h have been o btained, and diamond membranes of 0.3 to 0.9 mm thickness were achieved. Th e morphology of diamond films was generally formed of octahedrons with {111 } facets. This produced films that were unsuitable as flat layers due to th eir strong roughness. To obtain flat surfaces, {100} facet growth has been investigated on diamond films deposited on 2 in silicon seeded wafers at hi gh speed (15 to 30 mu m/h) and at a substrate temperature close to 900 degr ees C. The precursor gas mixture consisted of 2.2% methane in hydrogen, to which was added nitrogen (333 to 1000 ppm relative to hydrogen) or carbon d ioxide (0.6%), known to favour this growth selectivity. Then, [100] texture d polycrystalline films have been grown with {100} facets parallel to the s ubstrate surface and randomly aligned to each other. Raman spectroscopy has been applied for the identification of diamond film quality and its prefer red orientation. Over a wide spectral range of Raman analysis, the {111} an d {100} polycrystalline films have shown quite specific and well-defined si gnals, superimposed on the luminescence background. This aids identificatio n of the different morphologies, providing a film-specific signature. From {111} to {100} films, the luminescence maximum is shifted to higher wavenum bers, the shift being of the order of 1500 cm(-1). (C) 1999 Elsevier Scienc e S.A. All rights reserved.