Formation of crystalline heteroepitaxial SiC films on Si by carbonization of polyimide Langmuir–Blodgett films

Abstract

High-quality crystalline nano-thin SiC films on Si substrates were prepared by carbonization of polyimide (PI) Langmuir–Blodgett (LB) films. The obtained films were characterized by Fourier transform-infrared (FTIR) spectroscopy, X-ray diffraction (XRD) analysis, Raman spectroscopy, transmission electon microscopy (TEM), transmission electron diffraction (TED), and scanning electron microscopy (SEM). We demonstrated that the carbonization of a PI film on a Si substrate at 1000 °C leads to the formation of a carbon film and SiC nanocrystals on the Si substrate. It was found that five planes in the 3C-SiC(111) film are aligned with four Si(111) planes. As a result of repeated annealing of PI films containing 121 layers at 1200 °C crystalline SiC films were formed on the Si substrate. It was shown that the SiC films (35 nm) grown on Si(111) at 1200 °C have a mainly cubic 3C-SiC structure with small amount of hexagonal polytypes. Only 3C-SiC films (30 nm) were formed on the Si(100) substrate at the same temperature. It was shown that the SiC films (30–35 nm) can cover the voids with size up to 10 µm in the Si substrate. The current–voltage (I–V) characteristics of the n-Si/n-SiC heterostructure were obtained by conductive atomic force microscopy.