The surface of a semiconductor crystal[1] has many physical and chemical properties that dramatically affect both the fabrication process and electronic behavior[2] of the structure. In the fabrication process, adsorbed atoms, or adatoms, are epitaxially grown on a crystal in such a way that the structure of the grown crystal is dependent on the substrate structure. The substrate surface forms a template, or seed, from which deposited films may grow. The quality of the grown crystal structure depends almost entirely on the organization of substrate surface atoms.

To prepare a surface for the required quality of crystal growth, the surface must be free of contamination. Contamination-free semiconductor surfaces typically reconstruct to form a two-dimensional surface lattice dissimilar to the bulk lattice structure. Artificial forms of surface reconstruction, including deposition of a fractional monolayer (ML) of atoms (adatoms)[3][4][5][6][7][8][9] and high-temperature annealing[10], can be used to form various superstructures that alter the diperiodicity of the substrate surface. Other forms of reconstruction occur naturally in an effort to minimize the total free energy of the surface. These processes are considered.

Before detailed analysis of surface features was possible, it was known that surface doping of semiconductors altered the electronic properties of the metal-semiconductor (Schottky) interface[11]. Metal atoms alter intrinsic surface states and cause various defects. A study of the reconstructed Si surface is very important to the current investigation.

References