Photodetectors and terminators including a tapered thickness

Structures for a photodetector or terminator and methods of fabricating a structure for a photodetector or terminator. The structure includes a waveguide core, a light-absorbing layer having a sidewall, and a taper positioned adjacent to the sidewall of the light-absorbing layer. The taper extends laterally from the sidewall of the light-absorbing layer to overlap with the waveguide core, and the taper has a thickness that varies with position relative to the sidewall of the light-absorbing layer. For example, the thickness of the taper may decrease with increasing distance from the sidewall of the light-absorbing layer.