Active depth sensing image sensor

Aspects of the present disclosure relate to an image sensor. An example apparatus includes an image sensor including one or more pixels. Each pixel of the one or more pixels includes a photodetector, and the photodetector includes a photosensitive surface including germanium. In some implementations, the photodetector includes a photodiode including an intrinsic silicon layer doped with germanium or including germanium crystals. The intrinsic layer may be between a p− layer and an n− layer not including germanium. The intrinsic layer may be configured to absorb photons of the light received at the intrinsic layer. The light may include one or more reflections of an emitted light for active depth sensing. For example, the emitted light may be frequency modulated and having a first wavelength for indirect time-of-flight depth sensing. Sampling circuits may generate voltages indicating a phase difference between the emitted light and a reflection of the emitted light.