PHOTOINDUCED INTERSUBBAND ABSORPTION IN SI SIGE QUANTUM-WELLS/

We have investigated photoinduced infrared absorption in p-doped Si/Si Ge quantum wells. The absorption spectra exhibit two distinct features : free-carrier absorption and intersubband absorption in the valence b and. The photoinduced absorption in both p and s polarizations is foun d to depend on the carrier density and strongly differs from the origi nal absorption of the doped quantum wells. Photoinduced intersubband a bsorption is attributed to carriers away from the Brillouin zone cente r. We show that photoinduced intersubband absorption spectroscopy can provide useful information on valence band mixing effects in Si/SiGe q uantum wells. (C) 1995 American Institute of Physics.