Erbium in silicon–germanium quantum wells

Abstract

Strained Si 1− x Ge x /Si quantum wells have been doped with erbium by implantation. A comparison is made with strained Si 1− x Ge x /Si quantum wells and relaxed Si 1− x Ge x , with x between 10% and 25%, doped with erbium during MBE growth. The erbium concentration was between 1×10 18 and 5×10 18 cm −3 throughout the active regions. Transmission electron microscopy, X-ray diffraction, and photoluminescence studies indicate that good regrowth can been achieved after full amorphisation by implantation of the strained quantum wells. The erbium luminescence is more intense in the Si 1− x Ge x /Si layers, but erbium-implanted samples containing Si 1− x Ge x exhibit defect luminescence in the region of 0.9–1.0 eV. These defects are also present when Si 1− x Ge x /Si quantum wells are implanted with an amorphising dose of silicon, and then regrown. They are attributed to small germanium-rich platelets, rather than to erbium-related defects. Electroluminescence is presented from a forward biased erbium-implanted Si 0.87Ge 0.13/Si structure at a drive current density of only 1.8 mA/cm 2.