Pump-probe studies of photoluminescence of InP quantum wires embedded in dielectric matrix

Persistent changes in the photoluminescence (PL) spectra of InP quantum wir es (QWRs) embedded in chrysotile asbestos in the presence of the strong res onant narrow band excitation were observed. induced suppression and enhance ment of PL in different regions of spectra and the blue shift of the PL hav e been demonstrated. Three onsets related to the LA momentum conserving pho nons of InP have been observed in the changed spectrum. These spectral chan ges are long preserved at 2 K and depend an the intensity and the photon en ergy of strong resonant narrow-band excitation. They can be erased by the e xposure of the below-absorption-edge light. The observed spectral changes a re caused by trapping of charges at the surface of the nanostructures and t heir tunneling into traps in the matrix. The enhancement and suppression of PL of InP nanostructures can be explained by the competition of the follow ing processes: saturation of the capture centers by strong narrow-band reso nance light, charge-induced blue shift of the PL spectrum and Auger autoion ization and subsequent Auger quenching of radiative recombination of carrie rs. The large blue shift of the maximum of the PL under high excitation reg ime is caused by the strong Coulomb interaction anisotropy in semiconductor -insulator QWRs owing to the image charge effect. For comparison and better understanding of the origin of these effects, the experiment with InP quan tum dots embedded in chrysotile asbestos has also been carried out, (C) 199 9 Elsevier Science Ltd. All rights reserved.