Optoelectronic device
An optoelectronic device and method of making the same. The device comprising: a substrate; an epitaxial crystalline cladding layer, on top of the substrate; and an optically active region, above the epitaxial crystalline cladding layer; wherein the epitaxial crystalline cladding layer has a refractive index which is less than a refractive index of the optically active region, such that the optical power of the optoelectronic device is confined to the optically active region.
1. An optoelectronic device, comprising:
a substrate;
a crystalline cladding layer, on the substrate; and
a substrate-based optically active region, on the substrate and above the crystalline cladding layer,
wherein the crystalline cladding layer has a refractive index which is less than a refractive index of the optically active region.
2. The optoelectronic device of claim 1 , wherein the optoelectronic device is on a silicon on insulator (SOI) wafer, the SOI wafer comprising:
the substrate,
an insulating layer on top of the substrate, and
a silicon-on-insulator layer on top of the insulating layer.
3. The optoelectronic device of claim 2 , wherein the optically active region is an electro-absorption modulator or a photodiode.
4. The optoelectronic device of claim 2 , wherein the optically active region is formed of Si x Ge 1-x-y Sn y where 5%≤x≤20%, 1%≤y≤10%.
5. The optoelectronic device of claim 2 , wherein the crystalline cladding layer is formed of silicon or SiGe.
6. The optoelectronic device of claim 2 , further comprising a silicon seed layer between the crystalline cladding layer and the optically active region.
7. The optoelectronic device of claim 2 , wherein the optically active region comprises a silicon-germanium region.
8. The optoelectronic device of claim 2 , wherein a length of the optically active region is between 30 μm and 60 μm.
9. The optoelectronic device of claim 2 , wherein the insulating layer is on a first or second side of the crystalline cladding layer, and wherein an upper surface of the crystalline cladding layer has a height from the substrate substantially equal to a height from the substrate of an upper surface of the insulating layer.
10. The optoelectronic device of claim 2 , wherein the optically active region is within a cavity of the silicon-on-insulator layer.
11. The optoelectronic device of claim 2 , further comprising:
an input waveguide, coupled to a first side of the optically active region; and
an output waveguide, coupled to a second side of the optically active region,
wherein an interface between the input waveguide and the optically active region is oblique to a guiding direction of the input waveguide.
12. The optoelectronic device of claim 2 , wherein the optically active region includes a waveguide ridge, and has:
an upper surface and a lower surface;
a lower doped region, a portion of the lower doped region being located at or adjacent to a portion of the lower surface of the optically active region, the lower doped region extending laterally outwards from the waveguide ridge in a first direction;
an upper doped region, a portion of the upper doped region being located at or adjacent to a portion of the upper surface of the waveguide ridge of the optically active region, the upper doped region extending laterally outwards from the waveguide ridge in a second direction different from the first direction; and
an intrinsic region located between the lower doped region and the upper doped region.
13. The optoelectronic device of claim 2 , wherein the optically active region includes:
a ridge extending from the crystalline cladding layer;
a first slab region at a first side of the ridge and a second slab region at a second side of the ridge; and
wherein:
a first doped region extends within the first slab region and along a first sidewall of the ridge; and
a second doped region extends within the second slab region and along a second sidewall of the ridge.
14. The optoelectronic device of claim 2 , wherein the optically active region includes:
a ridge extending from the crystalline cladding layer, a portion of the ridge being formed from the material of the crystalline cladding layer and a portion of the ridge being formed from a semiconductor material which is different from the material of the crystalline cladding layer;
wherein the crystalline cladding layer includes a first slab region at a first side of the ridge and a second slab region at a second side of the ridge; and
wherein:
a first doped region extends within the first slab region and along a first sidewall of the ridge; and
a second doped region extends within along the second slab region and along a second sidewall of the ridge.
15. The optoelectronic device of claim 2 , wherein the optically active region includes:
a ridge extending from the crystalline cladding layer, a portion of the ridge being formed from the material of the crystalline cladding layer and a portion of the ridge being formed from a semiconductor material which is different from the material of the crystalline cladding layer;
a first slab region at a first side of the ridge and a second slab region at a second side of the ridge,
wherein:
the first slab region or the second slab region is formed from the material of the crystalline cladding layer;
a first doped region extends within the first slab region and along a first sidewall of the ridge; and
a second doped region extends within the second slab region and along a second sidewall of the ridge.
16. The optoelectronic device of claim 2 , wherein the optically active region includes:
a silicon base, disposed on top of the crystalline cladding layer;
a ridge extending from the silicon base, a portion of the ridge being formed from silicon and a portion of the ridge being formed from a semiconductor material which is different from silicon;
wherein the silicon base includes a first slab region at a first side of the ridge, and a second slab region at a second side of the ridge; and
wherein:
a first doped region extends within the first slab region and along a first sidewall of the ridge, the first sidewall contacting the first slab region; and
a second doped region extends within the second slab region and along a second sidewall of the ridge, the second sidewall contacting the second slab region.
17. The optoelectronic device of claim 2 , wherein the optically active region includes:
a waveguide ridge; and
a waveguide slab, and
wherein at least one of: a sidewall of the waveguide ridge; a portion of the waveguide slab; the entirety of the waveguide slab; a portion of the waveguide ridge adjacent to the waveguide slab; and both sidewalls of the waveguide ridge; is formed of crystalline or amorphous silicon and contains dopants.
18. The optoelectronic device of claim 17 , wherein the remainder of the waveguide ridge and waveguide slab is formed of SiGe, germanium, or SiGeSn.
19. The optoelectronic device of claim 2 , wherein the optically active region is formed of SiGe or SiGeSn having a first composition and the crystalline cladding layer is formed of SiGe or SiGeSn having a second composition different to the first composition.
20. The optoelectronic device of claim 2 , wherein the optoelectronic device is driveable at a voltage of between 1.8 V and 2 V.