Bhattacharya, ShuvodipJohnston, SteveDatta, SumanHudait, Mantu K.2025-03-032025-03-032023-05-192637-6113https://hdl.handle.net/10919/124761We report contactless effective minority carrier lifetime of epitaxially grown unstrained and in-plane <110> biaxially tensile-strained (001) germanium (ϵ-Ge) epilayers measured using microwave-reflectance photoconductance decay measurements. Strained Ge epilayers were grown using InxGa1-xAs linearly graded buffers on (001) GaAs substrates. Using homogeneous excitation of unstrained Ge epilayers, thickness-dependent separation of minority carrier lifetime components under low injection conditions yielded a bulk lifetime of 114 ± 2 ns and low surface recombination velocity of 21.3 ± 0.04 cm/s. More notably, an effective minority carrier lifetime of >100 ns obtained from sub-50 nm 1.6% tensile-strained Ge epilayers showed no degradation relative to the unstrained counterpart. Detailed material characterization using X-ray diffractometry revealed successful strain transfer of 0.61 and 0.89% to the Ge epilayers via InxGa1-xAs metamorphic buffers and confirms pseudomorphic growth. Lattice coherence observed at the ϵ-Ge epilayer and InxGa1-xAs buffer heterointerfaces via transmission electron microscopy substantiates the prime material quality achieved. The relatively high carrier lifetimes achieved are an indicator of excellent material quality and provide a path forward to realize low-threshold Ge laser sources.Pages 3190-3197application/pdfenIn Copyrightgermaniumcarrier lifetimetensile strainmolecular beam epitaxyx-ray diffractionphotoconductancebulk lifetimesurface recombinationvelocityArticle - Refereedhttps://doi.org/10.1021/acsaelm.3c0025656Hudait, Mantu [0000-0002-9789-3081]2637-6113