Reaction Processes At The Initial Stage of Diamond Nucleation on The Surface of Si(111)

Abstract

ABSTRACTThe thermal behavior of CHx(x=2–3) radicals and H atoms adsorbed on Si(111) surface was investigated using high-resolution electron-energy-loss spectroscopy (HREELS), quadrupole mass spectrometry (QMS), and low-energy electron diffraction (LEED). We found that CHx(x=2–3) radicals in the top adlayers of saturate adsorption were not stable, and the loose structures among a few top adlayers broke up completely till 550K. TDMS(thermal desorption mass spectrometry) analysis showed significant desorption of atomic hydrogen, CH2 and CH3. In the region of 550K-750K, only H2 was detected by TDMS, and we speculate that the CHx(x=2–3) species catenate each other, and form a network of hydrocarbon, which is possibly the initial stage of diamond nucleation on Si. This formed network was not stable above 800K, C2 hydrocarbon species were observed after the thermal desorption temperature was over 800K. HREELS measurement demonstrated that no H atoms existed when substrate temperature reached 980K. Compared with the result reported by S.-Tong Lee for diamond(Ref. 12), we conclude that low stability of hydrocarbon species on Si is the dominant reason that results in the difficulty of diamond nucleation on perfect Si surface.