Absorption of n -type Ge, Si quantum wells for normal incident radiation

The theory of electron intersubband infrared absorptions for n-type Si/GeSi and Ge/GeSi quantum wells in the waveguide structure is presented in order to compare with recently obtained experimental results. The absorption coefficient as a function of the polarization angle of incident light has been investigated by considering the degeneracies and the occupancies of the different valleys for conduction band.