We address nonradiative recombination pathways by leveraging surface passivation and dislocation management in micron-scale arrays of Ge crystals grown on deeply patterned Si substrates. The time decay photoluminescence (PL) at cryogenic temperatures discloses carrier lifetimes approaching 45 ns in band-gap engineered Ge micro-crystals. This investigation provides compelling information about the competitive interplay between the radiative band-edge transitions and the trapping of carriers by dislocations and free surfaces. Furthermore, an in-depth analysis of the temperature dependence of the PL, combined with capacitance data and finite difference time domain modeling, demonstrates the effectiveness of GeO2 in passivating the surface of Ge and thus in enhancing the room temperature PL emission.
Cite
@article{arxiv.1603.08700,
title = {Disentangling nonradiative recombination processes in Ge micro-crystals on Si substrates},
author = {F. Pezzoli and A. Giorgioni and K. Gallacher and F. Isa and P. Biagioni and R. W. Millar and E. Gatti and E. Grilli and E. Bonera and G. Isella and D. J. Paul and Leo Miglio},
journal= {arXiv preprint arXiv:1603.08700},
year = {2016}
}