Abstract: A photodetector structure over a partial length of a silicon waveguide structure within a photonic integrated circuit (PIC) chip. The photodetector structure is embedded within a cladding material surrounding the waveguide structure. The photodetector structure includes an absorption region, for example comprising Ge. A sidewall of the cladding material may be lined with a sacrificial spacer. After forming the absorption region, the sacrificial spacer may be removed and passivation material formed over a sidewall of the absorption region. Between the absorption region an impurity-doped portion of the waveguide structure there may be a carrier multiplication region, for example comprising crystalline silicon. If present, edge facets of the carrier multiplication region may be protected by a spacer material during the formation of an impurity-doped charge carrier layer. Occurrence of edge facets may be mitigated by embedding a portion of the photodetector structure with a thickness of the waveguide structure.