RAMAN-SPECTROSCOPY INVESTIGATION OF CUBIC BORON-NITRIDE SINGLE-CRYSTALS AND LAYERS ON SI(100)

Micro-Raman spectroscopy (mu-RS) measurements were performed on cubic boron nitride (c-BN) single crystals and c-BN thin films deposited on Si(100) by magnetron sputtering of a h-BN target. The 482.5 nm laser l ine of a Kr+ laser as well as the 458.0 nm laser line of an Ar+ laser were found to be most sensitive to the detection of c-BN. For single c rystals of different sizes (< 100 nm, 1 mu m, 100 mu m, 1 mm) and nano crystalline c-BN layers on Si(100) substrates the influence of the cry stal size on the frequency position and the lineshape of the longitudi nal (LO) and transversal optical (TO) phonon features was investigated . With decreasing crystal size a shift towards lower frequencies as we ll as a broadening and increasing asymmetry of the LO and TO phonon is observed. The comparison of these results with a phonon-confinement m odel is discussed. For the c-BN layers on Si(100) substrates, addition al two-dimensional Raman mappings of the Si signal were performed reve aling the influence of the transparent hard coating on the substrate. (C) 1997 Elsevier Science S.A.