In some embodiments, the present disclosure relates to a semiconductor device, including a substrate including a first semiconductor material and a semiconductor layer extending into an upper surface of the substrate and including a second semiconductor material with a different band gap than the first semiconductor material. The semiconductor device also includes a passive cap including a first dielectric material and disposed along the upper surface of the substrate and on opposite sides of the semiconductor layer, and a photodetector in the semiconductor layer. The first dielectric material includes silicon nitride.

Various embodiments of the present disclosure are directed towards an optoelectronic device. The device includes a substrate, and a germanium photodiode region extending into an upper surface of the substrate. The germanium photodiode region has a curved upper surface that extends past the upper surface of the substrate. A silicon cap overlies the curved upper surface of the germanium photodiode region. There is an absence of oxide between the curved upper surface of the germanium photodiode region and an upper surface of the silicon cap.

An integrated circuit includes a photodetector. The photodetector includes one or more dielectric structures positioned in a trench in a semiconductor substrate. The photodetector includes a photosensitive material positioned in the trench and covering the one or more dielectric structures. A dielectric layer covers the photosensitive material. The photosensitive material has an index of refraction that is greater than the indices of refraction of the dielectric structures and the dielectric layer.

Embodiments described herein may be related to apparatuses, processes, and techniques directed to a planar germanium photodetector that includes n-type and p-type amorphous silicon deposits on a germanium slab. During operation, a uniform electrical field is formed across the germanium bulk between the amorphous silicon deposits. Other embodiments may be described and/or claimed.

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.

A photodetector structure includes a first semiconductor material layer over a doped well in a substrate. The photodetector structure includes an air gap vertically between the first semiconductor material layer and a first portion of the doped well. The photodetector structure includes an insulative collar on the first portion of the doped well and laterally surrounding the air gap. The photodetector structure may include a second semiconductor material layer on the first portion of the doped well and laterally surrounded by the insulative collar. The photodetector structure may include a third semiconductor layer over the first semiconductor layer.

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 photovoltaic cell includes a germanium-containing well embedded in a single crystalline silicon substrate and extending to a proximal horizontal surface of the single crystalline silicon substrate, wherein germanium-containing well includes germanium at an atomic percentage greater than 50%. A silicon-containing capping structure is located on a top surface of the germanium-containing well and includes silicon at an atomic percentage greater than 42%. The silicon-containing capping structure prevents oxidation of the germanium-containing well. A photovoltaic junction may be formed within, or across, the trench by implanting dopants of a first conductivity type and dopants of a second conductivity type.

A semiconductor structure includes a waveguide structure on a substrate. The waveguide structure includes a first protrusion having a first dopant type; a first lower portion having the first dopant type; a second lower portion having a second dopant type, wherein the second dopant type is different from the first dopant type, and an interface of the first lower portion and the second lower portion defines a PN interface; and a second protrusion having the second dopant type. The semiconductor structure further includes a photoelectric material proximate the PN interface, wherein the photoelectric material extends above the PN interface.

A photonic device includes a substrate, a P-type doped component disposed over the substrate, an N-type doped component disposed over the substrate, an optical absorption layer disposed over the substrate, and a charging layer disposed over the substrate. The optical absorption layer is disposed between the P-type doped component and the N-type doped component. The optical absorption layer and the substrate have different material compositions. A charging layer is disposed between the P-type doped component and the N-type doped component. The charging layer has a first side surface that is substantially linear. The first side surface is in direct contact with the optical absorption layer.