Luminescence from porous silicon doped with erbium-ytterbium complexes

The study of photoluminescence (PL) from porous silicon (PS) containing complexes of gadolinium oxychloride with Er3+- and Er3+-Yb3+ is reported. The concentration dependencies of PL intensity of PS with Er3+ containing complex have been studied. The dependencies have retained the main features that are characteristic of the pure complex for both IR and visible regions of the PL spectra. This allows interpretation of PL processes in complex-containing PS through the concept of multiplication of low-energy electron excitations and cross-relaxation degradation of higher excited states. It has been shown that introducing Yb3+ ions into the complex signifcantly increases the PL intensity. Mechanisms associated with defect formation, the intrinsic conversion of excitation energy within Yb3+, and the conversion within Er3+ ions followed by transferring of elicitation energy to the Yb3+ ions has been considered. The PL polarization with excitation in the visible is reported as well. (C) 1999 Elsevier Science B.V. All rights reserved.