INTERFACIAL STRUCTURES OF ORIENTED DIAMOND ON SI(100) CHARACTERIZED BY CONFOCAL RAMAN-SPECTROSCOPY

We have characterized bias-assisted CVD diamond using the non-destruct ive technique of confocal Raman spectroscopy to investigate the interf acial structures and the variation in structure and quality with depth . The spectral depth profiles of oriented diamond showed that a band c entered at 1210 cm(-1) and the diamond peak at 1332 cm(-1) coexisted a t the interface between the oriented diamond and Si substrate. The rel ative intensity of the 1210 cm(-1) band compared to that of the diamon d peak varied with depth. The intensity of the band decreased and that of the diamond peak increased from the interface to the diamond surfa ce. The quality of the oriented diamond improved with the growth time. In contrast, for the randomly-oriented diamond, a band centered at 15 50 cm(-1) was observed, the diamond peak was shifted between -6 and 6 cm(-1) from the single crystal diamond peak at 1332.5 cm(-1) and the s pectral profile did not change with depth. No band at 1210 cm(-1) was seen in this case. We conclude that a non-diamond phase with a Raman b and at 1210 cm(-1) and a diamond phase coexist at the interface betwee n the oriented diamond and the Si substrate, and that this 1210 cm(-1) phase is therefore a characteristic feature of the nature of the diam ond-substrate bonding in oriented films. Speculations on the origin of the 1210 cm(-1) are also discussed. (C) 1997 Elsevier Science S.A.