Low temperature near band edge recombination dynamics in ZnO nanorods
2014 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 116, no 12, 123506- p.Article in journal (Refereed) Published
The recombination dynamics of neutral donor bound excitons ((DX)-X-o: I-4, I-6/6a) and near band edge defect-related emission in solution grown ZnO nanorods are investigated using steady state and time-resolved photoluminescence (PL) measurements. The effects of annealing are also studied. Low temperature steady state PL shows a systematic removal of the I-4 line after annealing at 450 degrees C and the subsequent domination of I-6a in these PL spectra. Additionally, the time decay of the I-4, I-6/6a, free exciton (FX), and basal plane stacking fault-related (BSF) PL transitions are studied as a function of annealing temperature. For the various annealing temperatures studied, the PL decay is described by a bi-exponential profile with a fast component (contribution from the surface) and slow component (related to bulk recombination). The fast component dominates in the case of as-grown and low temperature annealed samples (anneal temperatures up to 300 degrees C), suggesting the presence of surface adsorbed impurities. For samples annealed above 400 degrees C, the effects of the surface are reduced. The sample annealed at 850 degrees C produced an overall enhancement of the crystal quality. The underlying mechanisms for the observed PL characteristics are discussed based on near surface band bending caused by surface impurities.
Place, publisher, year, edition, pages
American Institute of Physics (AIP) , 2014. Vol. 116, no 12, 123506- p.
IdentifiersURN: urn:nbn:se:liu:diva-112055DOI: 10.1063/1.4896488ISI: 000342840000018OAI: oai:DiVA.org:liu-112055DiVA: diva2:763879
Funding Agencies|South Africa Research Chairs Initiative of the Department of Science and Technology; National Research Foundation (NRF), South Africa; Nelson Mandela Metropolitan University (NMMU); Swedish-South Africa research collaboration2014-11-172014-11-132015-01-23