The present disclosure relates to semiconductor structures and, more particularly, to lateral phototransistors and methods of manufacture. The structure includes a lateral bipolar transistor; and a T-shaped photosensitive structure vertically above an intrinsic base of the lateral bipolar transistor.

In some embodiments, the present disclosure relates to a single-photon avalanche detector (SPAD) device including a silicon substrate including a recess in an upper surface of the silicon substrate. A p-type region is arranged in the silicon substrate below a lower surface of the recess. An n-type avalanche region is arranged in the silicon substrate below the p-type region and meets the p-type region at a p-n junction. A germanium region is disposed within the recess over the p-n junction.

Structures including a photodetector and methods of forming a structure including a photodetector. The structure comprises a semiconductor layer comprising a crystalline semiconductor material, a waveguide core including a first sidewall and a second sidewall, and a photodetector including a light-absorbing layer, an anode, and a cathode. The light-absorbing layer includes a first portion and a second portion that are disposed on the semiconductor layer. The first portion of the light-absorbing layer is adjacent to the first sidewall of the waveguide core, and the second portion of the light-absorbing layer is adjacent to the second sidewall of the waveguide core.

A current-assisted photonic demodulator, including a detection portion produced based on germanium, containing at least two doped modulation regions and at least one doped collection region, surrounded by a peripheral lateral portion generating in the detection portion horizontal tensile and vertical compressive mechanical stress. The doped collection region(s) are disposed according to a vertical arrangement in relation to the doped modulation regions.

Structures for a photonic chip that include a photodetector and methods of forming such structures. The structure comprises a photodetector including a pad, a semiconductor layer on the pad, and a metal layer that extends into the pad. The semiconductor layer may be configured to absorb light of a given wavelength.