Strain Effects on the Transport and Optical Properties of the Silicon Germanium Alloy

Theoretical study of the transport and optical properties of a strained Si_{rm 1-x}Ge_{rm x} layer is presented in this dissertation. The band structure of the SiGe under the strain is studied first. The k cdot p method is employed to study the transport and optical properties in valence band structure. The effective masses and mobilities of the strained SiGe are then calculated. The mobility of the strained SiGe layer is shown to be increased as compared with the bulk Si due to the lifting of the valence band degeneracy and the smaller effective mass. Using an one-electron approximation, the intersubband transitions, confined-to-confined and confined -to-continuum transitions, are calculated and compared with the experimental data. The oscillator strength for conduction intersubband transitions is also calculated using an one -band model. The importance of the optical property in SiGe device is that the normal incidence is possible due to the s-p mixing for the p-type quantum well and the mass anisotropy for the n-type quantum well.