Performance of AlGaInP LEDs on silicon substrates through low threading dislocation density (TDD) germanium buffer layer

This is the authors' abstract. We don't add key points for this paper.

Performance of GaInP/AlGaInP multi-quantum wells light-emitting diodes (LEDs) grown on low threading dislocation density (TDD) Germanium-on-Silicon (Ge/Si) substrates are compared and studied. Three approaches are used to realize the low TDD Ge/Si substrates. The first approach is the two-step growth of Ge/Si substrate with TDD of ∼5 × 10 7 cm −2 . The second approach is through doped the Ge seed layer with arsenic (As) and TDD of <5 × 10 6 cm −2 can be achieved. The third approach is through wafer bonding and layer transfer techniques, germanium-on-insulator (GOI) substrate with TDD of ∼1.2 × 10 6 cm −2 can be fabricated. To demonstrate the quality of these Ge/Si substrates, LEDs fabricated on commercially available Ge/Si and bulk Ge substrates were also included for comparison purposes. The LEDs fabricated on the As-doped Ge/Si and GOI substrates exhibit superior performances, with output light intensity at least 2× higher compared to devices fabricated on commercially available Ge/Si substrate. These findings enable the monolithic integration of visible-band optical sources with Si-based control circuitry.