Erbium in silicon-germanium quantum wells

Strained Si1-xGex/Si quantum wells have been doped with erbium by implantat ion. A comparison is made with strained Si1-xGex/Si quantum wells and relax ed Si1-xGex with x between 10% and 25%, doped with erbium during MBE growth . The erbium concentration was between 1 x 10(18) and 5 x 10(18) cm(-3) thr oughout the active regions. Transmission electron microscopy, X-ray diffrac tion, and photoluminescence studies indicate that good regrowth can been ac hieved after full amorphisation by implantation of the strained quantum wel ls. The erbium luminescence is more intense in the Si1-xGex/Si layers, but erbium-implanted samples containing Si1-xGex exhibit defect luminescence in the region of 0.9-1.0 eV. These defects are also present when Si1-xGex/Si quantum wells are implanted with an amorphising dose of silicon, and then r egrown. They are attributed to small germanium-rich platelets, rather than to erbium-related defects. Electroluminescence is presented from a forward biased erbium-implanted Si0.87Ge0.13/Si structure at a drive current densit y of only 1.8 mA/cm(2). (C) 1999 Elsevier Science B.V. All rights reserved.