Photoinduced and equilibrium optical absorption in Ge/Si quantum dots

Abstract

The results of studies of the optical absorption spectra in Ge/Si quantum dot structures in the midinfrared region are reported. Two types of structur es different in terms of the method used for quantum dot formation and in terms of barrier layer thickness are explored. The photoinduced absorption associated with the nonequilibrium population of hole states and optical absorption in structures doped to different lev� els are investigated. Specific features that are associated with occupation of the ground and excited states of quantum dots and exhibit a polarization dependence are observed. From the experimental data, the energy spectrum of holes is determined for structures of both types.