화학공학소재연구정보센터
Applied Surface Science, Vol.255, No.10, 5561-5564, 2009
Photo-thermal effects induced by KrF laser in complex oxides investigated by time resolved pyrometry: Cases of Er-doped ZnO and Y2O3
To study the thermal/photon conversion of erbium-doped ZnO (ZnO: Er) substrates induced by UV pulsed laser, the rapid infrared pyrometry method is successfully used for monitoring the IR band (1-12 mm) emission in a hemispherical chamber under vacuum. Samples are irradiated with a homogeneous laser beam KrF (248 nm, 25 ns) which induces surface temperature rise. The laser induced thermal radiations are detected by a liquid nitrogen cooled detector (2-3 ns time rise). Semi-conductors doped erbium exhibit a complex behaviour under the KrF laser beam in the fluence range 200-400 mJ/cm(2). Actually, the relaxation time of the induced IR signal is too wide (ms) compared to undoped samples (ns). For a better understanding, samples ZnO: Er and erbium-doped Yttrium oxide (Y2O3:Er) are studied. The fact that erbium (Er) spectra shows a photoluminescence in the band 1400 1600 nm with a maximum at 1535 nm, the pyrometry signals include the energetic contribution of the PL phenomenon and the pure thermal one. To confirm this statement, a germanium filter is used to cut off the IR radiations less than 2000 nm. Finally, coherent results allowing thermal to photoemission conversion are discussed in the last part of this paper. (C) 2008 Elsevier B. V. All rights reserved.