Study of intersubband transitions in Si1-xGex/Si quantum wells using 14-band k⋅p model

Optical intersubband transitions (ISTs) for both in-plane polarization (TE) and normalto-plane polarization (TM) in p-type Si1-xGex/Si multiple quantum wells (MQWs) are investigated using 14-band k⋅p model combined with the envelope-function Fourier expansion method. The results show that the amplitudes of different intersubband transitions for TE and TM polarizations, and the overall absorption vary regularly with the well width as it affects the distribution of bound and continuum excited states directly, and TE mode absorption dominates in all the QWs studied. This work provides useful information for design and analysis of Si1-xGex/Si quantum well infrared photodetectors (QWIPs).