Investigation of the 4H-SiC surface

The silicon carbide (SiC) surface is more complex than that of silicon and can be carbon-terminated or silicon-terminated, and can exist as several reconstructions. Investigations of the surface structure as a function of temperature, under ultrahigh vacuum (UHV) conditions using scanning tunneling microscopy (STM) and low energy electron diffraction (LEED), are presented. The 4H-SiC surface can be passivated using a silicon deposition/evaporation technique to reconstruct the surface. This has a significant effect on the electrical behaviour of metal contacts to the silicon carbide surface, critical in any electronic device. Atomic resolution STM studies of the 4H-SiC surface have revealed step features and micropipe defects in unprecedented detail. STM has also been used to image clusters of metal deposited on the 4H-SiC surface. The effect of annealing on the behaviour of these nickel clusters is also presented. The surface of the silicon carbide is extremely important in the fabrication of silicon carbide electronic devices and this paper presents a discussion of the SiC surface with particular reference to its impact on SiC device applications in power electronics.