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We have investigated the luminescence emitted at 1.54 m from erbium-implanted strained ultrahigh vacuum chemical vapor deposition-grown ͑UHVCVD-grown͒ Si 1Ϫx Ge x quantum wells. Germanium fractions of up to 13% were used, and all well widths were below the critical thickness for pseudomorphic growth. A preliminary study was carried out on Si 1Ϫx Ge x quantum wells implanted with amorphizing doses of silicon at 77 K in order to study the regrowth across the interfaces, and subsequent structural and optical recovery. After amorphization and regrowth by a two stage anneal process, transmission electron microscopy ͑TEM͒ clearly showed the presence of the quantum wells, with sharp contrast. X-ray diffraction ͑XRD͒ studies showed that good regrowth has been achieved, with line widths very similar to the original material. However, the photoluminescence ͑PL͒ was found to be dependent upon the duration of the first anneal. Increasing the anneal time resulted in PL spectra being dominated by broad signals between 0.9 and 0.97 eV associated with structural defects. High concentrations of erbium were incorporated into the strained Si 1Ϫx Ge x quantum wells by implantation and solid phase epitaxial regrowth. TEM and XRD studies showed that the quantum wells retained their structure, with negligible segregation or diffusion of the germanium during the recrystallization. Erbium-related emission centered at 1.54 m was observed in the implanted Si 1Ϫx Ge x layers after regrowth, and generally found to be of similar intensity as that in bulk silicon implanted with more than an order of magnitude higher dose of erbium.

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Prospects of laser operation in erbium doped silicon has been analyzed by a Shockley-Read-Hall (SRH) model. Erbium atoms have been considered to be introducing strong recombination centers in the silicon lattice. Electron-hole recombination at these sites were considered to be the source of erbium excitation. A two level system was considered for calculation of optical gain and the laser threshold. For a laser cavity of 300 μm with mirror reflectivities of 90%, and an optimistic absorption coefficient of 5 cm-1, a population inversion of 1.4×1018/cm3 was estimated as the threshold value. Achievement of the lasing condition was found feasible, but only for certain conditions of erbium activation. Effects of nonradiative deexcitation routes have been analyzed. On the assumption of 1019/cm3 of active erbium sites, linear increase of optical power in the laser cavity has been estimated for injected carrier densities above 1018/cm3.