We report direct excitation of optically active Er centers in porous Si. Excitation spectroscopy performed close to the intracenter 4I15/2→4I11/2 and 4I15/2→4I9/2 transitions of Er3+ (4f11) ions allows us to identify two kinds of Er centers in porous Si: (i) Er diffused into porous nanograins with lower than cubic symmetry and (ii) Er centers incorporated in an amorphous silicalike matrix. The latter show much weaker thermal quenching of the Er3+ emission which decreases only by a factor of eight when the temperature is increased from 4.2 K up to 360 K.
|Number of pages||3|
|Journal||Applied Physics Letters|
|Publication status||Published - 27 Nov 1997|