An example Geiger mode avalanche photodiode includes a first semiconductor alloy forming a compositionally graded gain region configured to form a conduction band having free electrons, a valence band having free holes, and a bandgap between the valence band and the conduction band that varies in size across the graded gain region; a second semiconductor alloy forming an absorber region; and a semiconductor substrate.

An avalanche photodiode detector is provided. The avalanche photodiode detector comprises an absorber region having an absorption layer for receiving incident photons and generating charged carriers; and a multiplier region having a multiplication layer; wherein the multiplier region is on a mesa structure separate from the absorber region and is coupled to the absorber region by a bridge for transferring charged carriers between the absorber region and multiplier region.

An integrated circuit includes a substrate material that includes an epitaxial layer, wherein the substrate material and the epitaxial layer form a first semiconductor material with the epitaxial layer having a first conductivity type. At least one nanowire comprising a second semiconductor material having a second conductivity type doped differently than the first conductivity type of the first semiconductor material forms a junction crossing region with the first semiconductor material. The nanowire and the first semiconductor material form an avalanche photodiode (APD) in the junction crossing region to enable single photon detection. In an alternative configuration, the APD is formed as a p-i-n crossing region where n represents an n-type material, i represents an intrinsic layer, and p represents a p-type material.

A semiconductor light-receiving device includes: a semi-insulating substrate; and a buffer layer, a p-type contact layer, a light absorption layer, a p-type field alleviating layer, an avalanche multiplication layer, an n-type field alleviating layer and an n-type contact layer laminated in order on the semi-insulating substrate, wherein the buffer layer includes a superlattice obtained by alternately laminating an InP layer and an Al.sub.xGa.sub.yIn.sub.1-x-yAs layer (0.16x0.48, 0y0.31) and does not absorb light of a wavelength band absorbed by the light absorption layer.

An epitaxial grown avalanche photodiode (APD), the avalanche photodiode comprising an anode, a cathode, an absorber, and a doped multiplier. The absorber and the doped multiplier are about between the cathode and the anode. The doped multiplier has a multiplier dopant concentration. The doped multiplier substantially depleted during operation of the epitaxial grown photodiode. The doped multiplier may comprise of a plurality of multiplication regions, each of the multiplication regions substantially depleted during operation of the avalanche photodiode.

A waveguide photodetector includes a slab over a substrate, first and second contact portions protruding upward from the slab, and a ridge protruding upward from the slab between the first and second contact portions. A first semiconductor layer is over the substrate and includes a first doped region in the first contact portion, a second doped region in the slab between the first contact portion and the ridge, a third doped region and a sixth doped region in the ridge, a fourth doped region in the second contact portion, a fifth doped region in the slab between the second contact portion and the ridge, a first intrinsic region between the sixth and third doped regions, and a second intrinsic region between the sixth and fifth doped regions. A second semiconductor layer is over the first intrinsic region and between the sixth and third doped regions.

A method of operating an avalanche photodiode includes providing an avalanche photodiode having a multiplication region capable of amplifying an electric current when subject to an electric field. The multiplication region, in operation, has a first ionization rate for electrons and a second, different, ionization rate for holes. The method also includes applying the electric field to the multiplication region, receiving a current output from the multiplication region, and varying the electric field in time, whereby a portion of the current output is suppressed.

Disclosed is a photodetector with a resonant waveguide structure, including: a substrate; a light absorption layer located on the substrate and configured for detecting an optical signal; a resonant waveguide structure including a first waveguide portion and a second waveguide portion spaced apart; the first waveguide portion receives the optical signal and transmits the received optical signal to a first region of the second waveguide portion, the second waveguide portion includes a second region for coupling the optical signal to the light absorption layer, and the second waveguide portion provides a circular transmission path for transmission of the optical signal to transmit the optical signal that transmitted to the first region to the second region along part of the circular transmission path and retransmit the optical signal that flows through the second region without being coupled to the light absorption layer to the second region along the circular transmission path.

In one aspect, an avalanche photodiode, includes an absorber, a first superlattice structure directly connected to the absorber and configured to multiply holes and a second superlattice structure directly connected to the first superlattice structure and configured to multiply electrons. The first and second superlattice structures include III-V semiconductor material. The avalanche photodiode is a dual mode device configured to operate in either a linear mode or a Geiger mode. In another aspect, a method includes fabricating the avalanche diode.

Embodiments herein describe an APD with a vertical electric field. In one embodiment, to reduce the thickness of the vertical electric field, an inversion layer at the interface between N doped silicon and an oxide is used as a cathode for the vertical electric field.