Following the introduction and the motivation, the structure of the thesis is outlined as follows.
The second chapter provides an introduction to the band structure calculations. The principles of the empirical and the ab-initio approaches are described. Then the k ⋅ p method and the mechanisms of the spin relaxation in semiconductors are presented. Finally, the fundamental mechanisms of the spin relaxation in semiconductors are explained.
In the third chapter a two-band k ⋅ p Hamiltonian with shear strain and the intrinsic spin degree of freedom, developed near the X-point of the Brillouin zone, is explained. The subband spin-wave functions and their eigenenergies are calculated. The shear strain inflicted valley splitting is described.
The fourth chapter calculates the surface roughness induced spin relaxation matrix elements. The methods to calculate the spin lifetime due to the surface roughness, acoustic, and optical phonons are elaborated, and the calculated results are explained. The direction sensitive spin relaxation model is also highlighted. The major differences among the spin-flip and momentum scattering mechanisms are also investigated. Furthermore, the influence of the valley splitting in unstrained silicon films is elaborated.
In the fifth chapter a comprehensive study of the spin diffusion in silicon in presence or absence of the electric field, when spin is injected from a ferromagnetic semiconductor, is performed. The spin injecting source is assumed to be charge neutral; accumulated; and depleted. The major differences in the transport behavior are revealed. The spin diffusion in silicon from only a space charge layer is also scrutinized.
The sixth chapter summarizes the work, and describes an outlook for future work.