RHEED patterns of 3 nm carbon layer coated Si(111) surface using Sputtering

In order to overcome the high cost of SiC substrates, researchers reacted carbon atoms and Si surface to obtain SiC layers on Si substrate since one decade ago. The SiC is the best substrate to grow the graphene. In this work, 3 nm carbon layer was coated on the Si(111) surface using the Sputtering method. After the RCA cleaning process, n-type Si(111) with resistivity 1.5-4.5 Ω.m was put into the load lock chamber then transferred into the deposition chamber after the vacuum condition was attained. The carbon source was evaporated with plasma energy of 150 watts for 3 min to obtain about 3 nm carbon layer on Si(111) surface. The samples were characterized using ex-situ the reflection high energy electron diffraction (RHEED), the scanning electron microscopy (SEM) and the Raman spectroscopy. The sample was annealed at RT-1400°C while the transition of RHEED pattern was observed using the cooled CCD camera. The amorphous pattern appeared at RT-800°C, a combination of dot and ring patterns appeared at 850-1200°C and finally Si(111)-7×7 appeared at over 1200°C. Dot patterns were investigated as SiC structures. From SEM images, it is confirmed that triangle SiC formed on Si(111) surface. In addition formation of SiC on Si(111) was observed by Raman spectroscopy. (paper)