Abstract
Experimental and theoretical investigations of the near-band-gap optical nonlinearities in type-II GaAs/AlAs quantum wells are reported. The temporal evolution of the optical nonlinearities of different samples grown at our two different laboratories is analyzed by comparing femtosecond results at different pump-probe time delays with nanosecond measurements at different sample temperatures. The quasi-cw measurements at low temperatures show exciton bleaching and a pronounced heavy-hole exciton blueshift, which is absent at elevated plasma temperatures (congruent-to 100 K). Femtosecond spectra show a delayed onset of the exciton blueshift consistent with hole-plasma cooling in the absence of electrons. The results are analyzed using many-body theory assuming complete electron-hole charge separation. We show that the presence of a one-component plasma modifies the nonlinear optical behavior of the GaAs layer and results in dramatically different properties compared to type-I quantum-well structures.
| Original language | English |
|---|---|
| Pages (from-to) | 3043-3053 |
| Number of pages | 11 |
| Journal | Physical Review B: Condensed Matter and Materials Physics |
| Volume | 44 |
| Issue number | 7 |
| Publication status | Published - 15 Aug 1991 |