Integrated photodetector with embedded semiconductor region
View Patent ↗In some embodiments, the present disclosure provides an optical module. A waveguide includes a rib, and further includes a first protrusion and a second protrusion respectively on opposite sides of the rib. Further, the waveguide is formed of a first semiconductor material. A photodetector is in the waveguide and comprises a PN junction in the rib. A P type region of the PN junction extends to the first protrusion, and an N type region of the PN junction extends to the second protrusion. Further, the first and second protrusions accommodate heavily doped P and N type contact regions. A semiconductor region is on the PN junction. The semiconductor region comprises a second semiconductor material different the first semiconductor material. For example, the second semiconductor material may have a smaller bandgap than the first semiconductor material to enhance quantum efficiency.
1 . An optical module, comprising:
a waveguide comprising a rib and further comprising a first protrusion and a second protrusion respectively on opposite sides of the rib;
a PN junction between the first protrusion and the second protrusion; and
a semiconductor region of the waveguide on the PN junction, wherein the waveguide comprises a first semiconductor material, and the semiconductor region comprises a second semiconductor material different from the first semiconductor material, wherein the semiconductor region has a first width within the rib of the waveguide and has a second width beneath the rib of the waveguide, and wherein the second width is greater than the first width.
2 . The optical module of claim 1 , wherein the first semiconductor material comprises silicon and the second semiconductor material comprises germanium or a III-V semiconductor material.
3 . The optical module of claim 1 , wherein a position of the semiconductor region substantially coincides with a position in the waveguide which is at both a width-wise center of the waveguide and a height-wise center of the waveguide from a cross-sectional perspective.
4 . The optical module of claim 1 , further comprising a second waveguide comprising a second rib, a third protrusion, and a fourth protrusion respectively on opposite sides of the rib; and
a central region comprising a semiconductor material at a first end of the waveguide and at a second end of the second waveguide, the central region having a polygonal profile from a top-down view.
5 . The optical module of claim 1 , wherein the waveguide comprises a slab extending beneath the first protrusion and the second protrusion, and wherein the rib extends from the slab directly between the first protrusion and the second protrusion.
6 . The optical module of claim 5 , wherein the semiconductor region extends past outer sidewalls of the rib in a lateral direction and extends into the slab in a vertical direction.
7 . The optical module of claim 5 , wherein the semiconductor region is in the rib and extends into the slab of the waveguide with an inverted T-shaped profile.
8 . The optical module of claim 1 , further comprising a P-type region and an N-type region forming the PN junction, wherein the P-type region and the N-type region meet directly beneath the semiconductor region.
9 . The optical module of claim 8 , wherein the P-type region comprises a first heavily doped region with a first dopant concentration and a first lightly doped region with a second dopant concentration less than the first dopant concentration, and wherein the first heavily doped region extends from a top of the first protrusion to beneath the first protrusion.
10 . An optical module, comprising:
a central region having a polygonal profile from a top-down view;
waveguides surrounding the central region and ending at the central region, wherein the waveguides end at vertices of the polygonal profile of the central region and contact the vertices of the polygonal profile from a plurality of different directions;
photodetectors integrated into the waveguides surrounding the central region;
a first pad coupled to N-type regions of the photodetectors; and
a second pad coupled to P-type regions of the photodetectors.
11 . The optical module of claim 10 , further comprising:
amplitude modulators integrated into the waveguides; and
a third pad coupled to the amplitude modulators.
12 . The optical module of claim 10 , further comprising:
attenuators integrated into the waveguides; and
a third pad coupled to the attenuators.
13 . The optical module of claim 10 , further comprising:
semiconductor regions in the photodetectors, wherein the waveguides comprise a first semiconductor material and the semiconductor regions comprise a second semiconductor material different from the first semiconductor material; and
a third pad coupled to the semiconductor regions.
14 . An integrated device, comprising:
a first photodetector over a substrate and comprising a first central rib extending in a first direction and first peripheral ribs extending in the first direction and spaced from the first central rib in a second direction perpendicular to the first direction;
a first optical coupler coupled to the first photodetector by a first strip waveguide;
a second photodetector over the substrate and comprising a second central rib extending in a third direction different from the first direction and second peripheral ribs extending in the third direction and spaced from the second central rib in a fourth direction perpendicular to the third direction;
a second optical coupler coupled to the second photodetector by a second strip waveguide; and
a central region comprising a semiconductor material and coupled to the first photodetector and the second photodetector, wherein the central region and the first strip waveguide are at opposite ends of the first photodetector and wherein the central region and the second strip waveguide are at opposite ends of the second photodetector.
15 . The integrated device of claim 14 , wherein the first photodetector is spaced from the second photodetector by the central region.
16 . The integrated device of claim 14 , further comprising a plurality of additional photodetectors coupled to the central region, wherein the first photodetector, the second photodetector, and the plurality of additional photodetectors are equidistantly spaced around the central region.
17 . The integrated device of claim 14 , wherein the central region has a polygonal shape from a top-down perspective, and wherein the first photodetector and the second photodetector are coupled to vertices of the polygonal shape.
18 . The integrated device of claim 14 , wherein the central region further comprises a semiconductor cap and is configured to absorb photonic signals that pass through the first photodetector and the second photodetector.
19 . The integrated device of claim 14 , wherein the third direction is parallel to the second direction, and the fourth direction is parallel to the first direction.
20 . The integrated device of claim 14 , wherein the central region further comprises a sidewall extending from the first photodetector to the second photodetector, and wherein the sidewall extends in a fifth direction different from the first direction, the second direction, the third direction, and the fourth direction.