Adsorption and desorption kinetics of gallium atoms on 6H-SiC(0001) surfaces

Gallium (Ga) surface adsorption and desorption kinetics on 6H-SiC(0001) are investigated using reflection high-energy electron diffraction. It is foun d that for Ga adsorption, a wetting layer bonds strongly to the SiC(0001) s urface. Additional Ga atoms form droplets on top of the wetting layer. The Ga droplets behave like a metallic liquid. The activation energies for deso rption are determined to be 3.5 eV for Ga in the wetting layer and 2.5 eV f or Ga in the droplets. It is further found that the desorption of Ga atoms from the wetting layer follows a zero-order kinetics, i.e., the desorption rate is independent of the number of adsorbed atoms.