Adsorption Of Fullerene On Semiconductor Surfaces: A Density Functional Theory Study

As size of semiconductor devices continues the reduction trend, there is increasing demand for developing new chemistries on important semiconductor materials such as GaAs and the desired physical properties materials such as fullerenes. Chemisorption of fullerene on semiconductor surfaces is of current technological interest. Fullerenes represent one of the most novel materials in the past few years and their physicochemical properties have been extensively studied. Because of the inherent curvature and the highly delocalized π-orbitals, fullerenes are capable of reacting with a wide variety of substances. As low-k materials, fullerenes can become novel deposition precursors in the microelectronics industry. A large size variation of these molecules provides an excellent opportunity to design and develop novel materials for a broad range of applications.We present first principles studies using density functional theory under the generalized gradient approximation on adsorption mechanism, electronic properties and stability of fullerene molecules C_n (n=28, 32, 40, 44, 48, 60) on the c(4x4) reconstructed GaAs(001) surface and C₆₀ on the c(2x1) reconstructed Si(001) surface. Strong covalent bonds between fullerenes and the substrate are formed. In all cases, we found that upon fullerene adsorption the sites undergo considerable lattice relaxation and structural deformation of fullerene molecules also occur. The calculation yields physical insight into the adsorption mechanism and provides useful information on the properties of the materials.The dominant force for the chemisorption is the interaction between the empty π bands of fullerene, which acts as an electron acceptor, and the electron lone pairs of the p orbitals of As and the π electron of Si, which behaves as an electron donor. The...