In-plane resonant-cavity infrared photodetectors with fully-depleted absorbers
Resonant-cavity infrared photodetector (RCID) devices that include a thin absorber layer contained entirely within the resonant cavity. In some embodiments, the absorber is a single type-II InAs—GaSb interface situated between an AlSb/InAs superlattice n-type region and a p-type AlSb/GaSb region. In other embodiments, the absorber region comprises quantum wells formed on an upper surface of the n-type region. In other embodiments, the absorber region comprises a “W”-structured quantum well situated between two barrier layers, the “W”-structured quantum well comprising a hole quantum well sandwiched between two electron quantum wells. In other embodiments, the RCID includes a thin absorber region and an nBn or pBp active core within a resonant cavity. In some embodiments, the RCID is configured to absorb incident light propagating in the direction of the epitaxial growth of the RCID structure, while in other embodiments, it absorbs light propagating in the epitaxial plane of the structure.
1. A hybrid waveguide comprising a III-V resonant-cavity infrared detector (RCID) photodiode ridge integrated with a waveguide,
the waveguide comprising:
a first cladding layer disposed on a substrate;
a core layer disposed on the first cladding layer; and
a second cladding layer disposed on the core layer;
the core layer and second cladding layer being patterned to form air or dielectric regions on each lateral side of the hybrid waveguide, the air or dielectric regions being configured to laterally confine light propagating in the waveguide such that propagation is in a single lateral mode;
and the RCID ridge comprising:
a p + bottom contact layer disposed on an upper surface of the second cladding layer;
a p-type region disposed on a first area of an upper surface of the bottom contact layer;
an absorber region having a thickness of less than 100 nm disposed on an upper surface of the p-type region;
an n-type region disposed on an upper surface of the absorber region; and
an n + top contact layer disposed on an upper surface of the n-type region;
the hybrid waveguide further comprising a first distributed Bragg reflector (DBR) grating at a first end and a second DBR grating at a second end, the first and second DBR gratings forming a resonant cavity within the RCID photodiode extending along a length of the hybrid waveguide, the resonant cavity having a resonant wavelength λ R ; and
wherein the RCID photodiode is configured to detect infrared light propagating within the hybrid waveguide, the resonant cavity formed by the first and second DBR gratings being configured to increase an effective absorption path of light having at the resonant wavelength λ R travelling through the hybrid waveguide.
2. The hybrid waveguide according to claim 1 , wherein at least one of the first and second cladding layers is SiN and the core layer is silicon.
3. The hybrid waveguide according to claim 1 , wherein the p + bottom contact layer comprises p + -GaSb or p + -AlGaAsSb.
4. The hybrid waveguide according to claim 1 , wherein the p-type region comprises p-GaSb or p-AlGaAsSb.
5. The hybrid waveguide according to claim 1 , wherein the n-type region comprises an n-InAs/Al Sb superlattice.
6. The hybrid waveguide according to claim 1 , wherein the n + bottom contact layer comprises n + -InAsSb or an n + -InAs/AlSb superlattice.
7. The hybrid waveguide according to claim 1 , wherein at least one outside edge of the n-layer is ion-bombarded to form at least one ion-bombardment region having a predetermined extent of ion bombardment, the extent of ion bombardment being tailored to provide a predetermined reduction in surface current leakage in the RCID.
8. The hybrid waveguide in accordance to claim 1 , wherein the top metal contact is much narrower laterally than the top of the RCID ridge.
9. The hybrid waveguide according to claim 1 , wherein the n + top contact layer has a lateral width configured to minimize parasitic losses resulting from overlap of the propagating optical mode with the top contact metal.
10. The hybrid waveguide according to claim 1 , further comprising a top cladding layer having a low refractive index disposed between the n-type region and the n + top contact layer, the top cladding layer being configured to minimize mode penetration into the top contact metal.
11. The hybrid waveguide according to claim 1 , wherein the n + top contact layer is patterned along its longitudinal axis into a series of alternating contact stripes and non-contacted regions to provide a low-duty cycle top electrical contact.