For the development of photonic integrated circuits, it is mandatory to implement light sources on a Si-on-insulator (SOI) platform. However, point defects in the Si matrix and, e.g., at the Si/SiO₂ interface act as nonradiative recombination channels, drastically limiting the performance of Si-based light emitters. In this Letter, we study how these defects can be healed by applying an advanced hydrogenation process, recently developed in photovoltaic research for the passivation of performance-limiting defects in Si solar cells. Upon hydrogenation, we observe an increase in the room temperature photoluminescence (PL) yield by a factor of more than three for defect-enhanced quantum dots (DEQDs) grown on float-zone Si substrates, revealing the potential of this technique to passivate detrimental defects. For DEQDs grown using SOI substrates, the PL yield enhancement even exceeds a factor of four, which we attribute to the additional passivation of defects originating from the substrate. The results for SOI substrates are of particular interest due to their relevance for future photonic integrated circuits.

While light-emitting nanostructures composed of group-IV materials fulfil the mandatory compatibility with CMOS-fabrication methods, factors such as the structural stability of the nanostructures upon thermal annealing, and the ensuing photoluminescence (PL) emission properties, are of key relevance. In addition, the possibility of improving the PL efficiency by suitable post-growth treatments, such as hydrogen irradiation, is important too. We address these issues for self-assembled Ge quantum dots (QDs) that are co-implanted with Ge ions during their epitaxial growth. The presence of defects introduced by the impinging Ge ions results in pronounced PL-emission at telecom wavelengths up to room temperature (RT) and above. This approach allows us to overcome the severe limitations of light generation in the indirect-band-gap group-IV materials. By performing in-situ annealing, we demonstrate a high PL-stability of the defect-enhanced QD (DEQD) system against thermal treatment up to 600 °C for at least 2 h, even though the Ge QDs are structurally affected by Si/Ge intermixing via bulk diffusion. The latter, in turn, allows for emission tuning of the DEQDs over the entire telecom wavelength range from 1.3 µm to 1.55 µm. Two quenching mechanisms for light-emission are discussed; first, luminescence quenching at high PL recording temperatures, associated with the thermal escape of holes to the surrounding wetting layer; and second, annealing-induced PL-quenching at annealing temperatures >650 °C, which is associated with a migration of the defect complex out of the QD. We show that low-energy ex-situ proton irradiation into the Si matrix further improves the light emission properties of the DEQDs, whereas proton irradiation-related optically active G-centers do not affect the room temperature luminescence properties of DEQDs.

The intentional merging of epitaxial Ge on Si(001) quantum dots with optically active defect sites promises low‐cost applications such as room temperature (RT) light emitters in Si photonics. Despite recent progress in this field, important benchmarks, for example, the thermal stability of such a combination of low‐dimensional nanosystems, as well as the curing of parasitic charge‐carrier recombination channels, have been barely investigated thus far. Herein, the structural robustness of defect‐enhanced quantum dots (DEQDs) is examined under millisecond flash lamp annealing (FLA), carried out at sample temperatures up to 800 °C. Changes in the optical DEQD properties are investigated using photoluminescence spectroscopy performed in a sample temperature range from 10 to 300 K. It is demonstrated that FLA—in contrast to in situ thermal annealing—leads to only negligible modifications of the electronic band alignment. Moreover, upon proper conditions of FLA, the RT emission intensity of DEQDs is improved by almost 50% with respect to untreated reference samples.

Optical and optoelectronic properties of all-group-IV quantum dot light-emitters for which the optical properties are enhanced by in-situ implantation of heavy ions (DEQDs) are investigated. Research directions towards more efficient light-emission from DEQDs as well as considerations towards the microstructural investigation of DEQD-defects are elaborated.