Efficient upconvertion of photoluminescence via two-photon-absorption in bulk and nanorod ZnO
2012 (English)In: Applied physics. B, Lasers and optics (Print), ISSN 0946-2171, E-ISSN 1432-0649, Vol. 108, no 4, 919-924 p.Article in journal (Refereed) Published
Efficient upconversion of photoluminescence from donor-bound excitons is revealed in bulk and nanorod ZnO. Based on excitation power-dependent PL measurements performed with different energies of excitation photons, two-photon absorption (TPA) and two-step TPA (TS-TPA) processes are concluded to be responsible for the upconversion. The TS-TPA process is found to occur via a defect/impurity (or defects/impurities) with an energy level (or levels) lying within 1.14–1.56 eV from one of the band edges, without involving photon recycling. One of the possible defect candidates could be VZn. A sharp energy threshold, different from that for the corresponding one-photon absorption, is observed for the TPA process and is explained in terms of selection rules for the involved optical transitions.
Place, publisher, year, edition, pages
Springer, 2012. Vol. 108, no 4, 919-924 p.
National CategoryCondensed Matter Physics
IdentifiersURN: urn:nbn:se:liu:diva-81306DOI: 10.1007/s00340-012-5138-yISI: 000310537100033OAI: oai:DiVA.org:liu-81306DiVA: diva2:551443
funding agencies|Swedish Research Council|621-2010-3971|2012-09-112012-09-112015-05-28