A photodetector includes an insulating layer on a substrate, a first graphene layer on the insulating layer, a 2-dimensional (2D) material layer on the first graphene layer, a second graphene layer on the 2D material layer, a first electrode on the first graphene layer, and a second electrode on the second graphene layer. The 2D material layer includes a barrier layer and a light absorption layer. The barrier layer has a larger bandgap than the light absorption layer.

A method of detecting an optical signal, comprising the steps of: providing an avalanche photodiode (APD) comprising a multiplication region capable of amplifying an electric current, said multiplication region, in operation, having a first ionization rate for electrons and a second ionization rate for holes, wherein said first ionization rate is different in magnitude from said second ionization rate, and exposure to the optical signal causes an impulse response; exposing the APD to a modulating optical signal; providing an external circuit that induces an APD bias to the multiplication region; providing an external circuit for amplifying and processing an electric signal from the avalanche photodiode; and modulating the APD bias in a manner that is correlated with the optical signal.

Techniques for enhancing the absorption of photons in semiconductors with the use of microstructures are described. The microstructures, such as holes, effectively increase the absorption of the photons. Using microstructures for absorption enhancement for silicon photodiodes and silicon avalanche photodiodes can result in bandwidths in excess of 10 Gb/s at photons with wavelengths of 850 nm, and with quantum efficiencies of approximately 90% or more. Their thickness dimensions allow them to be conveniently integrated on the same Si chip with CMOS, BiCMOS, and other electronics, with resulting packaging benefits and reduced capacitance and thus higher speeds.

A photodetector includes an insulating layer on a substrate, a first graphene layer on the insulating layer, a 2-dimensional (2D) material layer on the first graphene layer, a second graphene layer on the 2D material layer, a first electrode on the first graphene layer, and a second electrode on the second graphene layer. The 2D material layer includes a barrier layer and a light absorption layer. The barrier layer has a larger bandgap than the light absorption layer.

Various embodiments of a compensated photonic device structure and fabrication method thereof are described herein. In one aspect, a photonic device may include a substrate and a functional layer disposed on the substrate. The substrate may be made of a first material and the functional layer may be made of a second material that is different from the first material. The photonic device may also include a compensation region formed at an interface region between the substrate and the functional layer. The compensation region may be doped with compensation dopants such that a first carrier concentration around the interface region of function layer is reduced and a second carrier concentration in a bulk region of functional layer is reduced.

A method of detecting an optical signal, comprising the steps of: providing an avalanche photodiode (APD) comprising a multiplication region capable of amplifying an electric current, said multiplication region, in operation, having a first ionization rate for electrons and a second ionization rate for holes, wherein said first ionization rate is different in magnitude from said second ionization rate, and exposure to the optical signal causes an impulse response; exposing the APD to a modulating optical signal; providing an external circuit that induces an APD bias to the multiplication region; providing an external circuit for amplifying and processing an electric signal from the avalanche photodiode; and modulating the APD bias in a manner that is correlated with the optical signal.

An imaging sensor system includes a pixel array having a plurality of pixel cells disposed in a first semiconductor layer, where each one of the plurality of pixel cells has a single photon avalanche diode (SPAD) disposed proximate to a front side of a first semiconductor layer. Each of the plurality of pixel cells includes a guard ring disposed in the first semiconductor layer in a guard ring region proximate to the SPAD, and also includes a guard ring region reflecting structure disposed in the guard ring region proximate to the guard ring and proximate to the front side of the first semiconductor layer. The imaging sensor system also includes control circuitry coupled to the pixel array to control operation of the pixel array, and readout circuitry coupled to the pixel array to readout image data from the plurality of pixel cells.

An Si/Ge SACM avalanche photodiodes (APD) having low breakdown voltage characteristics includes an absorption region and a multiplication region having various layers of particular thicknesses and doping concentrations. An optical waveguide can guide infrared and/or optical signals or energy into the absorption region. The resulting photo-generated carriers are swept into the i-Si layer and/or multiplication region for avalanche multiplication. The APD has a breakdown bias voltage of well less than 12 V and an operating bandwidth of greater than 10 GHz, and is therefore suitable for use in consumer electronic devices, high speed communication networks, and the like.

A lateral Ge/Si APD constructed on a silicon-on-insulator wafer includes a silicon device layer having regions that are doped to provide a lateral electric field and an avalanche region. A region having a modest doping level is in contact with a germanium body. There are no metal contacts made to the germanium body. The electrical contacts to the germanium body are made by way of the doped regions in the silicon device layer.

An avalanche photodiode includes a GeOI substrate; an IGe absorption layer configured to absorb an optical signal and generate a photo-generated carrier; a first p-type SiGe layer, a second p-type SiGe layer, a first SiGe layer, and a second SiGe layer, where a Si content in any one of the SiGe layers is less than or equal to 20%; a first SiO.sub.2 oxidation layer and a second SiO.sub.2 oxidation layer; a first taper type silicon Si waveguide layer and a second taper type silicon Si waveguide layer; a heavily-doped n-type silicon Si multiplication layer; and anode electrodes and a cathode electrode.