Effects of hydrogenated amorphous carbon interlayer on diamond nucleation

Abstract

Diamond was deposited at 850 degrees C by microwave plasma chemical vapor deposition (CVD) on the interlayers with various intensity ratios (I-D/I-G) Of the D band (similar to 1400 cm(-1)) to the G band (similar to 1570 cm(-1)) in the Raman spectra, Diamond could be grown only on the interlayers with higher I-D/I-G (greater than or equal to 1.95), and N-d was slightly increased to 3 X 10(6)/cm(2) with I-D/I-G. The predeposition at 350 degrees C, which decreased the full-width at half-maximum of the broad D band, further increased N-d to 5 X 10(7)/cm(2). With 300 Angstrom Pt overlayer on the interlayer, N-d was much more enhanced to 8 X 10(7)/cm(2). We suggest the sp(3) bonded carbon clusters within the interlayer contribute to diamond nucleation, but they should be survived against atomic hydrogen etching during diamond deposition by increasing the sp(3)/sp(2) ratio, by increasing the degree in clustering, or by protecting them with overlayer.