High performance germanium on silicon photodiodes for back-end-of-line photonic integration

Integration of near-infrared photodetectors in the back-end-of-line requires low temperature growth of Ge (< 450(circle)C). We have fabricated high performance, vertical incidence Ge-on-Si photodiodes under thermal budget constraints with as-grown diodes achieving an internal quantum efficiency (IQE) of 38% and a dark current density of J(d) = 272 mu A/cm(2) at a reverse bias of V-r = 5V and a wavelength of lambda = 1310 nm. The photodiode design incorporates a remote heterointerface, demonstrating that Ge material quality is sufficiently high for minority carriers to diffuse to the Ge/Si interface. Post-growth annealing improves device performance, including 500 C-circle 3 h exposure that improves IQE to 57% and J(d) = 165 mu A/cm(2). Low-temperature grown Ge-on-Si photodiodes give comparable performance to diodes processed at high temperatures despite thermal budget constraints. (c) 2023 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license