We experimentally study III-V/Ge heterostructure and demonstrate InGaAs hetero-contacts to n-Ge with a wide range of In % and achieve low contact resistivity (ρC) of 5×10−8Ω⋅cm2 for Ge doping of 3×1019cm−3. This results from re-directing the charge neutrality level (CNL) near the conduction band and benefiting from low effective mass for high electron transmission. For the first time, we observe that the heterointerface presents no temperature dependence despite the two different conduction minimum valley locations of III-V (Γ-valley) and Ge (L-valley), which potentially stems from elastic trap-assisted tunneling through defect states at the interface generated by dislocations. The hetero-interface plays a dominant role in the overall ρC below ≈1×10−7Ω⋅cm2, which can be further improved with large active dopant concentration in Ge by co-doping.
@article{arxiv.2106.15099,
title = {Low Resistance III-V Hetero-contacts to N-Ge},
author = {Junkyo Suh and Pranav Ramesh and Andrew C. Meng and Aravindh Kumar and Archana Kumar and Shashank Gupta and Raisul Islam and Paul C. McIntyre and Krishna Saraswat},
journal= {arXiv preprint arXiv:2106.15099},
year = {2021}
}