Surface properties of III-V semiconductors

In this work, Structural and electronic properties of both clean and GaAs coated surfaces of (1x1) Si(110) had been investigated by using CASTEP software. Parameters which have been used in calculations investigated by making systematic series of optimizations on Si and GaAs bulk crystals. After a decision on parameters, a structure of (1x1) Si(110); which has 7 layers of silicon, a bottom layer which is passivized by hydrogens and with 10 Å vacuum region on top had been given to a geometry optimization with 180 eV of cut-off energy. Structural changes and energy band diagram had been examined by the results. By holding 10 Å vaccum region constant, 1, 2 and 3 layers of GaAs had been coated over this structure. Geometric formation and energy band diagrams had been examined after a geometry optimization calculation. After calculation, direct energy gaps had been found by values in range 0,5 - 0,7 eV Key Words : Silicon, III-V semiconductor, CASTEP, DFT, surface