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 Si/Ge SACM avalanche photo-diodes (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.

An avalanche photodiode (APD) array with reduced cross talk comprises, in the illustrative embodiment, a 2D array of Geiger-mode APDs, wherein a via is formed through the backside (substrate) of each APD in the array.

Techniques for enhancing the absorption of photons in semiconductors with the use of microstructures are described. The microstructures, such as pillars and/or holes, effectively increase the effective absorption length resulting in a greater 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.

A multicolor imaging device capable of imaging two or more wavelengths with a single pixel comprises an avalanche photodiode having a material composition such that only one carrier causes substantially all of the impact ionization that occurs within the photodiode. The photodiode is arranged such that, when reverse-biased, the photodiode's gain varies with the photon energy of incident light. The photodiode, preferably a PIN avalanche photodiode or a separate absorber-multiplier photodiode, produces an output signal which can include at least two components produced in response to two different wavelengths of incident light. Circuitry receiving the output signal would typically include a means of extracting each of the components from the output signal.

A ultraviolet detector includes a substrate; a first epitaxial layer that is a heavily doped epitaxial layer and located on the substrate, a second epitaxial layer located on the first epitaxial layer, where the second epitaxial layer is a lightly doped epitaxial layer, or a double-layer or multi-layer structure composed of at least one lightly doped epitaxial layer and at least one heavily doped epitaxial layer; an ohmic contact layer located on the second epitaxial layer or formed in the second epitaxial layer, where the ohmic contact layer is a graphical heavily doped layer; and a first metal electrode layer located on the ohmic contact layer.

An optical sensing apparatus including: a substrate including a first material; an absorption region including a second material different from the first material; an amplification region formed in the substrate and configured to collect at least a portion of the photo-carriers from the absorption region and to amplify the portion of the photo-carriers; an interface-dopant region formed in the substrate between the absorption region and the amplification region; a buffer layer formed between the absorption region and the interface-dopant region; one or more field-control regions formed between the absorption region and the interface-dopant region and at least partially surrounding the buffer layer; and a buried-dopant region formed in the substrate and separated from the absorption region, where the buried-dopant region is configured to collect at least a portion of the amplified portion of the photo-carriers from the amplification region.

A diode radiation sensor having charge multiplication diodes and comprising a substrate with a front and a rear surface; a first layer of a semiconductor material doped with a first type of doping and arranged on the front surface of the substrate; a second layer of a semiconductor material doped with a second type of doping of electrically opposite sign to the first type and arranged to create a high electric field region between the first and the second layer; a third layer of a semiconductor material doped with a the second type of doping; a first isolation region interposed between a lateral edge of a charge multiplication diode and the first and the second layer of the semiconductor materials and extending into the substrate from the front surface to the third layer so as to create a working area electrically separated from the first and the second layer.

The present invention relates to a photodetector array for capturing image data, comprising: photodetector cells arranged on a substrate, each including a single-photon avalanche diode, wherein the active areas of the photodetector cells are neighbored along a hexagonal grid; microlenses, having a hexagonal or circular shape, each arranged on one photodetector cell to focus light onto the photodiode.

Various embodiments of a novel structure of a Ge/Si avalanche photodiode with an integrated heater, as well as a fabrication method thereof, are provided. In one aspect, a doped region is formed either on the top silicon layer or the silicon substrate layer to function as a resistor. When the environmental temperature decreases to a certain point, a temperature control loop will be automatically triggered and a proper bias is applied along the heater, thus the temperature of the junction region of a Ge/Si avalanche photodiode is kept within an optimized range to maintain high sensitivity of the avalanche photodiode and low bit-error rate level.