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

Abstract

Persistent changes in the photoluminescence (PL) spectra of InP quantum wires (QWRs) embedded in chrysotile asbestos in the presence of the strong resonant narrow band excitation were observed. Induced suppression and enhancement of PL in different regions of spectra and the blue shift of the PL have been demonstrated. Three onsets related to the LA momentum conserving phonons of InP have been observed in the changed spectrum. These spectral changes are long preserved at 2 K and depend on the intensity and the photon energy of strong resonant narrow-band excitation. They can be erased by the exposure of the below-absorption-edge light. The observed spectral changes are caused by trapping of charges at the surface of the nanostructures and their tunneling into traps in the matrix. The enhancement and suppression of PL of InP nanostructures can be explained by the competition of the following processes: saturation of the capture centers by strong narrow-band resonance light, charge-induced blue shift of the PL spectrum and Auger autoionization and subsequent Auger quenching of radiative recombination of carriers. The large blue shift of the maximum of the PL under high excitation regime 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 quantum dots embedded in chrysotile asbestos has also been carried out.