A photodiode and a related method of manufacture are disclosed. The photodiode includes a transfer gate and a floating diffusion adjacent to the transfer gate. In addition, the photodiode includes an upper terminal; an intrinsic semiconductor region in contact with the upper terminal, the intrinsic semiconductor region in a trench in a substrate adjacent to the transfer gate; and a lower terminal in contact with the intrinsic semiconductor region. An insulator layer is along an entirety of a sidewall of the intrinsic semiconductor region and between the intrinsic semiconductor region and the transfer gate. A p-type well may also optionally be between the insulator layer and the transfer gate.

A stacked (or vertically arranged) photodetector having at least one contact region on a germanium sensing region. Including the at least one contact on the germanium sensing region reduces the amount of surface area of the germanium sensing region that is interfaced with a substrate (e.g., a silicon substrate) in which the germanium sensing region is included. This reduces the amount of lattice mismatch reduces the amount of misfit defects for the germanium sensing region, which reduces the dark current for the photodetector. The reduced amount of dark current may increase the photosensitivity of the photodetector, may increase low-light performance of the photodetector, and/or may decrease noise and other defects in images and/or light captured by the photodetector, among other examples.

A photodetector includes a substrate, an absorber, a first doped region, and a second doped region. The absorber includes a first region and a second region that is more heavily doped than the first region. The first doped region is positioned on the substrate such that the first doped region contacts the second region of the absorber. A portion of the first doped region is positioned between the absorber and the substrate. The second doped region is positioned on the substrate such that the second doped region contacts the first region of the absorber rather than the second region of the absorber. A portion of the second doped region is positioned between the absorber and the substrate. The portion of the second doped region extends across a majority of a width of the absorber.