caa a22 4500 38807583X CHVBK 20180307125159.0 cr unu---uuuuu 161130e199909 xx s 000 0 eng 10.1557/S0883769400053033 doi S0883769400053033 pii (NATIONALLICENCE)cambridge-10.1557/S0883769400053033 Lasing in Rare-Earth-Doped Semiconductors: Hopes and Facts [Elektronische Daten] Semiconductors doped with rare-earth (RE) elements have attracted a lot of attention as alternative materials for producing electrically pumpe d semiconductor lasers whose emission wavelength is very weakly dependent on temperature. This prospect is especially attractive in the case of indirect-gap Silicon, whose photonic applications as the material for light emitters still remain more of a hope than a reality. In view of a desirable emission wavelength at 1.5 μm, a lot of research has concentrated on Si:Er (see Coffa et al. for a recent review). It is generally recognized that doping with Er ions presents one of the most promising approaches to Silicon photonics. However, despiteintensive investigations, stimulated emission has not been conclusively demonstrated for Si.Er or for any other RE-doped semiconductor. This is in striking contrast to optical amplifiers and lasers based on various erbium-doped glasses. In this article, which builds on recent articles in MRS Bulletin on Silicon photonics, we will address the issues relevant to efficient light generation by semiconductors doped with RE elements in general, and specifically by Si:Er-based structures. The intraimpurity electronic structure of RE ions is dominate d by electron-electron and spin-orbit interactions within the 4f shell. In the case of Er3+, they produce separated J-multiplets with 4I15/2 and 4I13/2 as the ground and the lowest-lying excited states, respectively. Due to the effective Screening of 4f electrons by the outer electron Shells, the host has a very limited influence and changes only slightly the relative positions of the levels. Depending on a particular site symmetry, the even terms of the crystal field split the free-ion J-multiplets into the Stark components typically by several meV for the ground State. The energy-level diagram of an Er3+ ion in a cubic crystal field is shown in Figure 1, where the energy transfer paths relevant for Si:Er are also schematically indicated. The odd terms of the crystal field potential admix the states of opposite parity to the 4f 11 configuration of the Er3+ ion, thereby introducing a certain degree of electric-dipole strength into the otherwise forbidden intra-4f-shell transitions. This effect enhance s slightly the magnetic-dipole strength of the 4I15/2 ↔ 4I13/2 transition and is host- and site-dependent. There-fore, Er-related center s of different microstructure can be fairly easily identified. Copyright © Materials Research Society 1999 Gregorkiewicz T. Langer J.M. MRS Bulletin Cambridge University Press 24/9(1999-09), 27-32 0883-7694 24:9<27 1999 24 MRS https://doi.org/10.1557/S0883769400053033 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1557/S0883769400053033 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Gregorkiewicz T. NATIONALLICENCE 700 1- Langer J.M. NATIONALLICENCE 773 0- MRS Bulletin Cambridge University Press 24/9(1999-09), 27-32 0883-7694 24:9<27 1999 24 MRS CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-cambridge