Band-edge photoluminescence in polycrystalline ZnO films at 1.7K

Activation of visible up-conversion luminescence in transparent and conducting ZnO:Er:Yb films by laser annealing

“…However, some authors assign it to zinc interstitial positions [19]. When the emission is yellow, orange and red, like in our case, it is mainly related to an excess of oxygen [18,20], oxygen interstitials [21][22][23] or zinc vacancies [20]. In our measurements we observe that the ratio of the intensities for visible defects-related band in respect to the UV band-to-band radiative recombination is much larger for the air annealed sample, which indicates a significant incorporation of oxygen and, thus, a reduction of oxygen vacancies.…”

“…The shape and position of this visible band depend on the defect state populations. In the case of green emission, it is mostly associated with oxygen vacancies [18]. However, some authors assign it to zinc interstitial positions [19].…”

Structural and optical characterization of pure and starch-capped ZnO quantum dots and their photocatalytic activity

“…These emission behaviors are believed that whenever quantum confinement takes place their bandgap nature changes from indirect to direct bandgap Hu and Chen 2008;Yang et al 2008). Usually, bulk ZnO does not show this much of luminescence behavior because of their indirect bandgap nature (Studenikin et al 2000). When having direct bandgap for capped/doped materials, wider PL is possible, whereas from the ZnO/starch QDs, we have observed an interesting broad blue emission spectrum from violet to green region, maximum at 440 nm which is due to the recombination electrons being trapped in random surface holes.…”

Multicolor Luminescence from Semiconductor Nanocrystal Composites Tunable in an Electric Field

“…The bands at 373.6 and 382.8 nm, as indicated by arrows in Fig. 3.13, might be attributed to donor-acceptor pair recombination (Tomzig & Helbig, 1976) or exciton phonon replicas (Reynolds & Collins, 1969) or two photon transitions (Studenikin et al, 2000). An additional radiation using the Ar + laser leads to the strong quenching of the UV emission up to approximately 55% with some changes in deep-level PL [ Fig.…”

“…The origin of the A-line emission is currently under discussion. Possible assignments of the A-line include: neutral excitons bound to nitrogen impurities (Look et al, 2002;Yang et al, 2006), donor-acceptor pair recombination , free-to neutral-acceptor transitions (Cao et al, 2007), two-electron transition of exciton bound to neutral donor (Studenikin et al, 2000), the first longitudinal optical (LO) phonon replica of free excitons (Hirai et al, 2008) or excitons bound to surface or structural defects ( Fallert et al, 2007;Fonoberov et al, 2006;He et al, 2007;Meyer et al, 2004;Teke et al, 2004). Recently, on a basis of cathodoluminescence measurements, it was suggested that this line is composed of two overlapped bands related to point defects and the first LO phonon replica of the free exciton (Mass et al, 2008).…”