A photodiode structure is based on the use of a double junction sensitive to different wavelength bands based on a magnitude of a reverse bias applied to the photodiode. The monolithic integration of a sensor with double functionality in a single chip allows realization of a low cost ultra-compact sensing element in a single packaging useful in many applications which require simultaneous or spatially synchronized detection of optical photons in different spectral regions.

Structures and techniques introduced here enable the design and fabrication of photodetectors (PDs) and/or other electronic circuits using typical semiconductor device manufacturing technologies meanwhile reducing the adverse impacts on PDs' performance. Examples of the various structures and techniques introduced here include, but not limited to, a pre-PD homogeneous wafer bonding technique, a pre-PD heterogeneous wafer bonding technique, a post-PD wafer bonding technique, their combinations, and a number of mirror equipped PD structures. With the introduced structures and techniques, it is possible to implement PDs using typical direct growth material epitaxy technology while reducing the adverse impact of the defect layer at the material interface caused by lattice mismatch.

A photodiode structure is based on the use of a double junction sensitive to different wavelength bands based on a magnitude of a reverse bias applied to the photodiode. The monolithic integration of a sensor with double functionality in a single chip allows realization of a low cost ultra-compact sensing element in a single packaging useful in many applications which require simultaneous or spatially synchronized detection of optical photons in different spectral regions.

Various particular embodiments include a method for forming a photodetector, including: forming a structure including a barrier layer disposed between a layer of doped silicon (Si) and a layer of germanium (Ge), the barrier layer including a crystallization window; and annealing the structure to convert, via the crystallization window, the Ge to a first composition of silicon germanium (SiGe) and the doped Si to a second composition of SiGe.

An optical device for detecting a first chemical species and a second chemical species contained in a specimen, which includes: a first optical sensor, which may be optically coupled to an optical source through the specimen and is sensitive to radiation having a wavelength comprised in a first range of wavelengths; and a second optical sensor, which may be optically coupled to the optical source through the specimen and is sensitive to radiation having a wavelength comprised in a second range of wavelengths, different from the first range of wavelengths.

The subject matter disclosed herein relates to formation of silicon germanium devices with tensile strain. Tensile strain applied to a silicon germanium device in fabrication may improve performance of a silicon germanium laser or light detector.

Forming an optical device includes growing an electro-absorption medium in a variety of different regions on a base of a device precursor. The regions include a component region and the regions are selected so as to achieve a particular chemical composition for the electro-absorption medium included in the component region. An optical component is formed on the device precursor such that the optical component includes at least a portion of the electro-absorption medium from the component region. Light signals are guided through the electro-absorption medium from the component region during operation of the component.

Various particular embodiments include a method for forming a photodetector, including: forming a structure including a barrier layer disposed between a layer of doped silicon (Si) and a layer of germanium (Ge), the barrier layer including a crystallization window; and annealing the structure to convert, via the crystallization window, the Ge to a first composition of silicon germanium (SiGe) and the doped Si to a second composition of SiGe.

A superlattice cell that includes Group IV elements is repeated multiple times so as to form the superlattice. Each superlattice cell has multiple ordered atomic planes that are parallel to one another. At least two of the atomic planes in the superlattice cell have different chemical compositions. One or more of the atomic planes in the superlattice cell one or more components selected from the group consisting of carbon, tin, and lead. These superlattices make a variety of applications including, but not limited to, transistors, light sensors, and light sources.

A photovoltaic device, particularly a solar cell, comprises an interface between a layer of Group III-V material and a layer of Group IV material with a thin silicon diffusion barrier provided at or near the interface. The silicon barrier controls the diffusion of Group V atoms into the Group IV material, which is doped n-type thereby. The n-type doped region can provide the p-n junction of a solar cell in the Group IV material with superior solar cell properties. It can also provide a tunnel diode in contact with a p-type region of the III-V material, which tunnel diode is also useful in solar cells.