Surface analysis of ultraprecise polished chemical vapor deposited diamondfilms using spectroscopic and microscopic techniques

Chemical vapor deposited (CVD) diamond films of varying crystallographic or ientations and sizes were thermochemically polished on steel plates. The si zes of the grains constituting the films used in this work ranged between 1 0 and 100 mum. Images of the surface morphologies of the films were obtaine d by the scanning electron microscope (SEM) before and after polishing. A s tylus profilometer was used to determine the surface roughness (arithmetic mean deviation) of the as-grown diamond films. The average surface roughnes s was found to be about 30 mum on the growth side and about 7 mum on the su bstrate side. Polishing for several hours at temperatures between 750 and 1 000 degreesC thinned the surface roughness down to about 1.3 and 1.5 nm on the growth and substrate sides, respectively, of the film as measured by th e atomic force microscope. Raman spectroscopy revealed low energy nondiamon d carbon lines in the frequency range between 200 and 700 cm(-1) on polishe d surfaces of optical graded diamond films in addition to the usual graphit e bands situated between 1350 and 1580 cm(-1). Photoluminescence and cathod oluminescence spectra of both polished and unpolished films revealed nitrog en and silicon as the only detectable defect centers in the films. The Rama n spectra of polished optical grade films also contained lines that are att ributed to molecular nitrogen complexes (N-2) at a frequency of 2438 cm(-1) , carbon-hydrogen (C-H-n) stretching vibrations at frequencies ranging from 2700 to 3200 cm(-1) and molecular hydrogen complexes (H-2) at a frequency of 4350 cm(-1). (C) 2001 American Institute of Physics.