The Photoluminescence Excitation Characteristics of the As2s3 Glass

THE PHOTOLUMINESCENCE EXCITATION CHARACTERISTICS OF THE AS2S3 GLASS

I. Baník1, R. Banik1, M. Kubliha2, M. Balažoviech1

1Department of Physics, Faculty of Civil Engineering, Slovak University of Technology, Radlinského 11, 810 05 Bratislava, Slovak Republic 2Department of Physics, Faculty of Materials Science and Technology, Slovak University of Technology, Bottova 25, 917 24 Trnava, Slovak Republic e-mail: [email protected]

This paper addresses the problem of the photoluminescence efficiency of excitation radiation in noncrystalline semiconductors from the view of the barrier-cluster model. The photoluminescence excitation characteristics (PLE characteristic) of the chalcogenide As2S3 has the following typical pattern: photoluminescence intensity increases with the increase of the photon energy hf, in line with the absorption a growth. Photoluminescence in this region copies the course of absorption α. The higher energies of the exciting photons in the region of exponential tail absorption will continue to increase exponentially, but photoluminescence will pass through the maximum and will decrease with further increase in photons energy. Up to that time, there is no generally accepted model which could explain and observe the facts. It appears that a barrier-cluster-heating model of a non-crystalline semiconductor is able to explain several significant phenomena in chalcogenide glasses. The observed experimental result is - as we believe - due to the action of free electrons that suppress photoluminescence. At lower photon energies, many generated generated e-h pairs recombine radiantly (radiative). There is a negligibly small number of free electrons in the solid. At low photon energies, electrons pass through low-energy optical passages in the area of potential barriers. Tunneling through potential barriers is therefore unlikely at low photon energy. Photoluminescence is pronounced - free electrons do not push it. At higher photon energies tunneling electrons through potentional barriers runs on higher energy levels, which strongly increases the probability of s-fold tunnelling of some electrons to larger distances. In this way the production of free electrons increases considerably with the increase of energy of exciting photons and consequently, also the amount of non-radiant recombinations. The number of radiant transitions, and thus also the photoluminescence level, decrease.

Forma prezentácie: poster, oral