Correlation Of Photoluminescence Research Articles

Photoluminescence Spectroscopy of Neutron-Irradiated Cubic SiC Crystals

Photoluminescence (PL) spectroscopy has been used to characterize neutron-irradiated cubic silicon carbide crystals. The effects of thermal annealing (600-1100OC) on the PL bands have been studied. Several PL bands consisting of a sharp line and its phonon replicas have been observed in the 9-80 K temperature range. Certain of them like the D1 spectrum doublet with 1.975 eV and 1.977 eV zero-phonon lines (ZPL) at 9 K and the L2 spectrum with ZPL at 1.121 eV were reported previously for ion-implanted and electron irradiated 3C-SiC crystals, respectively. Besides, some new bands with ZPL at 2.027, 1.594, 0.989 and 0.844 eV and a broad band at 1.360 eV have been found. A correlation of PL and EPR spectra intensities of these neutron-irradiated and annealed cubic SiC crystals is briefly discussed.

Organometallic vapor phase epitaxy of Er, O-codoped GaAs using tris(dipivaloylmethanato)erbium

Er,O-codoped GaAs (GaAs:Er,O) was grown by organometallic vapor phase epitaxy (OMVPE) using tris(dipivaloylmethanato)erbium [(C11H19O2)3Er: Er(DPM)3] at different growth temperatures (Tg). In photoluminescence (PL) measurements, Er-related PL lines partly assigned as an Er-2O center were observed in the samples grown at Tg = 500 – 550° C. The result revealed that the self formation of Er-2O center was accomplished by an incorporation of oxygen atoms in the Er(DPM)3 source. In the dependence of a H2 flow rate through the Er source on the PL properties, the intensity of the Er-related PL increased as that of the band-edge PL of GaAs host decreased. The correlation of PLs shows a highly efficient energy-transfer from GaAs host to the 4f-shell of Er ions in the GaAs:Er,O samples.

Morphological changes in porous silicon nanostructures: non-conventional photoluminescence shifts and correlation with optical absorption

In this paper, we show that the photoluminescence (PL) shifts of p-type porous silicon (PS) are mainly attributed to some morphological changes related to anodisation conditions. We discuss how differences in the stirring and nature of the electrolytic solution can lead to morphological changes of the PS layers. It has been found that when PS is formed in pure aqueous HF solution, it can exhibit a non-conventional and reproducible “porosity – PL peak relationship”. By correlating the PL spectral behaviour and PS morphology throughout a quantum-confinement model, we explain both conventional and non-conventional PL shifts. Correlation of PL and optical absorption (OA) shows that the PL peak energy and the optical absorption edge of PS exhibit the same trend with size effect. The spectral behaviour of OA with regard to that of PL is well analysed within the quantum-confinement model throughout the sizes and shapes of the nanocrystallites forming PS. The value of the effective band gap energy determined from the calculated lowest PL energy almost corresponds to that estimated from the optical absorption coefficient. These results suggest that the lowest radiative transition between the valence band and the conduction band corresponds to the largest luminescent wires, and that the radiative recombination process leading to the PL emission occurs in the c-Si crystallite core.